HP Proliant MicroServer Gen8

Table of Contents

HP’s compact entry level small business server is back with a much anticipated update. The MicroServer Gen8 has a sleeker design than the original, much faster Ivy Bridge based processors, and more extensive server features. What of the noise? ADDENDUM Oct 7, 2014: Using a Standard 4-Pin PWM Fan in the HP Microserver Gen8.

HP ProLiant MicroServer Gen8

January 17, 2014 by Lawrence Lee with Mike Chin

HP ProLiant MicroServer Gen8
Street Price

The original HP
ProLiant MicroServer
was an intriguing product when it was released
a couple of years ago, an x86 server PC with a low power mobile AMD processor,
four cold-swap hard drive bays, RAID 0/1, and ECC memory support, all stuffed
into a delightfully compact enclosure. Though it drew the attention of enthusiastic
home users it was designed with small businesses in mind, companies not large
enough to justify a bulky blade or rackmount server, but with needs that outstripped
simpler NAS box servers. It was also quiet and energy efficient enough that
we’re using one as SPCR’s primary storage device for quite sometime with few
hiccups. Our review article, which includes details on how to mod the non-standard
PWM wiring fan for lower noise, immediately caught tech readers’ attention and
continues to attract readership today, with total reads now at 640,000 —
double that of the next most popular article from 30 months ago — and still
climbing steadily.

The MicroServer Gen8, a much anticipated update, brings with it a tightened
design, faster hardware, and a few extra features. The Gen8’s footprint is slightly
larger than the original but replacing the full-sized optical drive with a slim
model (not included) took 3.7 cm off the top. This change plus a move from rounded
edges to sharper, more angular contours, gives it a sleeker look. The top of
the case has a shallow square inset designed so a matching network switch, the
, stacks flush against it. The drive bays are hidden behind a well-ventilated
plastic silver door which provides a nice contrast compared to the monotone
black MicroServer from 2011.

The MicroServer Gen8.


The Gen8 ships in a plain, sturdy box with with thick foam frames protecting
the enclosure. Our sample included a power cable and a few things for the optical
drive bay: a couple of SATA cables, a slimline SATA adapter, and a faceplate
if you prefer not to use a drive. A slim DVD burner was pre-installed in our
review unit but HP doesn’t offer this as an option on any of its pre-configured
Gen8 variants. They also included a copy of Windows Server 2012 Essentials which
runs about US$380 (OEM) and supports 25 users and 50 devices. You can
use whatever operating system you see fit, whether it be another flavor of Windows
or a free alternative like FreeNAS and any number of Linux distributions, but
no desktop OSes at all, only server OSes. Necessary drivers are provided for:

Microsoft Windows HPC Server 2008 R2
Microsoft Windows Server 2008 Essential Business
Microsoft Windows Server 2008 Foundation Edition
Microsoft Windows Server 2008 R2
Microsoft Windows Server 2008 R2 Foundation Edition
Microsoft Windows Server 2008 W32
Microsoft Windows Server 2008 x64
Microsoft Windows Server 2012
Microsoft Windows Server 2012 R2
Microsoft Windows Small Business Server 2011 Standard and Essentials
Microsoft Windows Storage Server 2008 R2
Red Hat Enterprise Linux 6 Server (x86)
Red Hat Enterprise Linux 6 Server (x86-64)
SUSE Linux Enterprise Server 11 (AMD64/EM64T)
SUSE Linux Enterprise Server 11 (x86)
Ubuntu 12.04
VMware ESXi 5.0
VMware vSphere 5.1
VMware vSphere 5.5

So the idea of slapping Windows 7 on this machine for a quick and easy home
server does not work. We tried and failed with Windows 7 x64; there are too
many non compatible drivers.

HP currently offers the Gen8 in three different flavors. The premium US$860
model sports a Pentium G2020T, 4GB of RAM and 1TB of storage, along with a MS
OS, described only as "MS WS12 Ess FIO en/fr/es/xc SW". The other
two are barebones models with no included storage, 2GB of RAM and your choice
of either a Pentium G2020T (US$455) or Celeron G1610T (US$390).
None of these come with OS installed, but a reseller can obviously accomplish
this task if required. Our review unit appears to be the bare G2020T model with
the memory upgraded to 8GB (2x4GB), and the aforementioned slim DVD writer which
isn’t standard. If you add the cost of these additions, you’re looking at a
total of about US$595. (Editor’s Note: The aformentioned
prices were hiked a bit sometime in the last couple of weeks; new prices are
cited in the table below.)

Specifications: HP ProLiant MicroServer Gen8
Available Configurations
Model No.
Intel Pentium G2020T (2.5 GHz, 3MB, 35W)
Intel Pentium G2020T (2.5 GHz, 3MB, 35W)
Intel Celeron G1610T (2.3 GHz, 2MB, 35W)
System RAM
Street Price
Common Specifications
(from the
product web page
Form factor
(fully configured)
Ultra Micro Tower
Power supply type (1) 150W non-hot plug, non redundant power supply kit Multi-output
Expansion Slots (1) PCIe; detail descriptions reference the QuickSpec
Memory slots 2 DIMM slots
Memory type PC3-12800E
Storage (hard drives) Supports up to (4) LFF SATA non-hot plug drives
Storage (optical) None ship standard
Network controller 1Gb 332i Ethernet Adapter 2 Ports per controller
Storage controller (1) Dynamic Smart Array B120i/ZM
(W x D x H)
22.97 x 24.51 x 23.24 cm
Weight 6.8 kg (without drives)
Infrastructure management iLO Management Engine, Insight Control (optional)
Warranty 1/0/0 – Server Warranty includes one year of parts, zero year of labor, zero year of onsite support coverage. Additional information regarding worldwide limited warranty and technical support is available at HP website.

All variants of the Gen8 include a 150W internal power supply, a low profile
PCI-E expansion slot, and two DIMM slots. The machine’s two gigabit ethernet
ports and four cold-swap hard drive bays are connected to HP controllers, while
an additional Marvell controller (not listed) is provided for one extra SATA
port which was hooked up to the optical drive in our sample. The standard warranty
is very basic, only covering parts for one year — the buyer is responsible
for support. HP offers a variety of extended server warranties, of course.


The MicroServer Gen8 is almost a perfect steel cube with dimensions of 23.0 x 24.5 x 23.2 or 9.1 x 9.6 x 9.1 inches (W x H x D), giving it a total volume of 13.1 liters. It’s about an inch deeper than the original but both the width and height have been slimmed down; overall it’s about 10% smaller.

A peek at rear reveals a removable motherboard tray with a low profile expansion slot, a 40 mm fan for the internal power supply, and a 140 mm exhaust fan servicing the rest of the system. The cover is held on with a pair of permanently-attached thumbscrews.

While there is a Kensington lock slot at the back, there’s nothing to stop an thief from simply swiping all your hard drives in a matter of seconds as the door covering them doesn’t have a lock. The power button, USB ports, and optical drive are all exposed at the top as well so clearly security was not on HP’s priority list.

While HP claims the new MicroServer is tool-less, low and behold, there’s a service tool attached to the front bezel. Torx screws are used to secure the drives to their caddies.

The drive trays are sturdy enough. Slits have been cut into the
front to maximize airflow though the drives appear to block them fairly

The rails guiding the caddies are shallow but work well enough. Several holes have been cut to improve airflow.

Despite having only two thumbscrews, the cover fits snugly. We have
to point out that like on the original Microserver, these are our favorite
type of case cover screws: Beefy, spring loaded, captive thumbscrews
that cannot be lost.

There is a bit more connectivity at the back than the previous MicroServer. There are 2 x USB 2.0 and 2 x USB 3.0 ports, a VGA connector, and two gigabit ethernet jacks. A third RJ45 port is separated from the others and is used to access HP’s ILO feature (Integrated Lights-Out) which allows access and maintenance to be performed remotely.


HP and other OEM server cases, especially those designed for enterprise/business
use, are fairly modular in order to facilitate easier service. The Gen8 adheres
to this philosophy as well. With a fixed drive cage and compact physical dimensions,
it can be difficult to maneuver inside the chassis delicately. Still, it’s an
improvement over the messier interior of the first
. The overall fit, sturdiness and modular design are excellent
compared to just about any desktop system or case.

The slim optical drive at the top is mounted to a frame that can be removed by pushing on a simple lever clamp. It you do not require an optical drive, it’s possible to replace it with a 2.5 inch SATA drive, an SSD perhaps.

The drive cage sits over motherboard tray, a fanless CPU heatsink, and the DIMM slots. Our review unit had 2x4GB of Samsung DDR3-1600 ECC memory pre-installed.

The PWM exhaust fan has an unusual 6-pin connector and five wires.
This design combined with the the server’s built-in fail-safes makes
it incredibly difficult to mod/replace.
More on this

The individual SATA data and power cables have been paired off and consolidated into the backplane.

With a 35W processor and only four hard drive bays, a modest power supply is all that is required. HP opted for a FlexATX 150W unit manufactured by Delta.

The SATA data cables are bundled together into one port, though there is a standalone standard SATA port next to it for the optical drive.


The original MicroServer used an embedded low power AMD mobile processor soldered
to the socket. The Gen8 uses an LGA1155 board with a replaceable processor like
most desktop PCs. The heatsink doesn’t use a standard mounting mechanism and
it’s passively cooled, so there are undoubtedly some TDP limitations.

As a fixed drive cage hangs over mainboard, a removable tray that
slides out the back allows full board access possible.

In addition to a full-sized (but low profile) PCI-E slot, additional connectivity is provided in the form of a USB port and microSD slot directly on the board.

The CPU is mated to a fanless heatsink with a thin thermal film.

The optical drive is powered by a floppy drive power connector plugged into a slimline SATA adapter. As there are no extra PSU connectors provided, some modification is required to replace the optical drive with a standard SATA drive. We removed a male plug off an old floppy drive and wired it to a SATA power cable to add an SSD.

A 2.5 inch drive is slim enough to fit in the optical drive bay and a piece of foam is sufficient to keep it in place. Using an SSD may be preferable if you want all of the hard drives’ capacity for actual storage rather than to house an O/S and to avoid any overhead this may cause.

A long frosted strip of light at the bottom indicates hard drive activity in purple/blue while the power LED at the top is a more demure green.


System Configuration:

Test configuration device listing.

Measurement and Analysis Tools

Timed Benchmark Test Details

  • Photoshop: Image manipulation using a variety of filters, a derivation
    of Driver Heaven’s Photoshop
    Benchmark V3
    (test image resized to 4500×3499).
  • WinRAR: Archive creation with a folder containing 68 files of varying
    size (less than 50MB).
  • iTunes: Conversion of an MP3 file to AAC.
  • TMPGEnc: Encoding a XVID AVI file with VC-1.

Testing Procedures

The system was put through various load states while system temperatures were recorded as well as power consumption and noise. Given this is a server product, it was tested with and without all four drive bays populated. The acoustic properties of the drives used are detailed below.

Test Drive Noise Summary
1-10 (10 = no vibration)

Idle Airborne Acoustics @1m

Seagate Barracuda XT 2TB
17 dBA
Samsung F3 EcoGreen 2TB
15~16 dBA
WD Caviar SE16 320GB
18~19 dBA
WD Red 3TB
13~14 dBA

Our usual array of CPU performance tests was also performed but some were excluded due to hardware (the Matrox GPU) or software (Windows Server 2012) incompatibility.

Network testing was also conducted but as they are not yet part of our standard testing procedures, they are detailed later in the review.


Getting the server up and running was reasonably straightforward — pretty
much the same process as any PC without an O/S. However, if you don’t have a
spare monitor, mouse, and keyboard handy, HP allows you to set it up remotely
via its ILO (Integrated Lights-Out) management technology. All you need to do
is turn on the MicroServer and connect two ethernet cables (one goes into a
dedicated ILO port) and use any other system on the same internal network to
access it via a remote console; the credentials required are printed on a cardboard
tag hanging off the back of the system.

ILO is a popular feature on all of HP’s Enterprise grade servers so it’s presence
on the MicroServer is somewhat surprising. Unfortunately, there’s a caveat that
makes it too good to be true. Health monitoring, diagnostics, and power cycling
over a web-based GUI are all possible but the remote console stops working when
the operating system starts loading, so it’s only good for initial setup and
for making changes in the BIOS. To get unrestricted access to the remote console
and other additional functionality, you need to acquire an upgraded ILO license,
with the Essentials package being the cheapest at a cost of $150 for three years.

Installation of Windows Server 2012 proceeded without any issues and all the
hardware worked out of the box, though it’s advisable to update any available
drivers from the HP website. The Windows Server 2012 incorporates features of
Windows 8 like the tile-based start screen (only less colorful) which makes
little sense on a PC without a touch screen and even less so on a server. With
an Ivy Bridge CPU, plenty of RAM, and a SandForce-based SSD, the server was
fairly snappy and responsive when used directly. The system takes a long time
to start up, as the boot process involves a lot of hardware checking that requires
more than two minutes before the Windows loading screen appears.

As the Gen8 utilizes a C204 chipset motherboard that lacks support for processor
graphics, the Pentium G2020T’s Intel HD IGP was set aside in favor of a Matrox
G200 graphics chip. You don’t need a powerful or even modern GPU for a server
but we were surprised to find the picture quality very poor, as if accessing
it through a remote desktop that had scaled down the color to maximize performance.
We thought it was a driver issue before realizing the GPU is ancient and subject
to color depth limitations which we haven’t seen in over a decade. At resolutions
of 1280×1024 and above, it can only output 16-bit color, and video playback
doesn’t work except for the most basic of formats. If you want the Gen8 to double
as a HTPC, you’ll need a discrete low-profile PCI-E graphics card with HDMI
audio capability (there’s no integrated sound card).


The first MicroServer boasted a modest noise level of 23 dBA@1m when empty
and could be made even quieter by replacing the fan. The Gen8 is far louder,
measuring 29 dBA@1m, primarily due to the large exhaust fan spinning at a high
speed throughout testing. There is no option in the BIOS or software that can
slow it down. The fan’s unique wiring and the fail-safes built into the Gen8
also make it resistant to speed modification. From what we can tell, the stock
fan doesn’t have any obvious acoustic flaws, so it would probably sound fairly
smooth when slowed down. However, extensive research and hands-on experimentation
failed to enable any kind of fan slowdown that did not trigger shutdown of the
entire system. (Editor Mike Chin described his frustrations with the Gen8 fan
in his notes at the end of this review.)

With four hard drives (which vary from 13 to 17 dBA@1m individually out in
the open) installed, the SPL increased by only 1 dB. The drives also introduced
some vibration to the enclosure as one would expect but it was a moderate amount.
Resonance effects were only noticeable at short distances and keep in mind our
combination of test drives vibrate a bit more than say the WD
and NAS
series which are the most popular consumer NAS/server drives.


Thermal testing confirmed the stock fan runs more than fast enough. Three of
our four hard drives never broke 30°C during testing. The energy efficient
CPU also didn’t require much in the way of cooling; on load the system power
consumption increased by only ~15W compared to idle. Load heated up the processor
to only 45°C and did not affect any of the drive temperatures.

System Measurements
Drive Configuration
SSD only
SSD + four hard drives
System State
CPU Load
CPU Load
CPU Temp
SSD Temp
HD Temp #1
HD Temp #2
HD Temp #3
HD Temp #4
System Power (AC)
29 dBA
30 dBA
Ambient temperature: 21°C.



Comparing our the Gen8’s thermal results to several mini-ITX cases we’ve previously
tested with the same hard drive configuration once again depicts the exhaust
fan as overaggressive. The other builds were significantly quieter and had hard
drive temperatures well under 40°C for the most part. The Gen8 boasts unbeatable
temperatures but it comes at a high acoustic price.

System Measurement Comparison (Four Hard Drives, Idle)
Lian Li PC-Q18
Chenbro SR30169
Fractal Node 304
HP ProLiant MicroServer Gen8
Pent. G2020T
CPU Cooling
Scythe Big Shuriken 2
Noctua NH-L9i
Noctua NH-U12P
Stock (fanless)
Power Supply
CM Silent Pro M700W
AcBel CE2 300
CM Silent Pro M700W
Delta DPS-150AB-5 A
System Fan Speed(s)
500 RPM
CPU Temp
HD #1 Temp
HD #2 Temp
HD #3 Temp
HD #4 Temp
System Power (AC)
21~22 dBA
23 dBA
23~24 dBA
30 dBA
Ambient temperature: 21°C.

While the Gen8 is tailor-made for server duty and is equipped with a 35W chip,
its idle consumption was barely less than the Lian
Li PC-Q18
and Fractal
Node 304
builds which were both equipped with a heavy duty ATX power
supply. The Cooler Master M700W isn’t anywhere near peak efficiency at this
power level so the MicroServer should have an advantage. Of course, it’s hard
to tell what effect all of the Gen8’s additional server features has on the
overall power draw.

Energy Efficiency (Single 2.5 inch SSD/HDD)

*originally tested with 2 x 3.5 inch drives; results adjusted to reflect power difference

The horsepower of a Ivy Bridge based desktop CPU increases energy consumption
considerably compared to the original MicroServer. The original was equipped
with a much less capable AMD Athlon II Neo chip but it used 9W less when idling
and 13W less on full load. We included a couple of NUC
configurations for comparison to give you an idea of how much more energy efficiency
could have been eked if HP had opted to use the latest mobile hardware. These
tiny boxes are more frugal with power yet still much faster than the first MicroServer.
Using an external power brick might have also helped bring the power draw down.
A 95W adapter would be enough to drive any of HP’s Gen8 configurations along
with four hard drives.


To get a sense of CPU performance, we performed a few of our usual CPU benchmarks. The Pentium G2020T equipped with our sample configuration is a competent dual core chip despite lacking features like Hyper-threading and Turbo Boost. It was only a tad slower than the Core i5-4250U in our tests.


For our network performance tests, we used one of our lab’s PCs as a main server and conducted a couple of different tests from it. Three different systems were used for comparison: the Gen8, and two custom builds with different integrated NICs. All the machines tested were running Windows 7 except for the Gen8, which was loaded with Server 2012. Data was transferred between SandForce-based SSDs to prevent any possible drive bottlenecking, and additionally, the SSDs were configured as secondary drives to avoid any O/S overhead. All traffic flowed through an unmanaged D-Link gigabit switch. There’s nothing special about our network — all our hardware is consumer grade.

First we benched each machine using LAN Speed Test, a network benchmark tool configured to transfer 10 packets successively with packet sizes of 1MB, 10MB, and 100MB. The program was run on our server and three runs of each test were performed with the results averaged.

Our custom builds using a pair of older Intel-based desktop motherboards performed similarly to one another in these tests but the MicroServer fared poorly by comparison. The results were particularly disappointing when transferring 1MB and 10MB packets. At 100MB, it caught up in writes but reads were more than 20% slower.

For a real world test, we initiated a manual file transfer from our designated server, copying a batch of 99 files of varying sizes totaling 1,741MB. Three runs were conducted both ways, with the results averaged.

Performance of all the machines was rather dismal compared to the theoretical top speed of a gigabit network with none of the systems cracking 200 mbps (25 MB/s) though transferring multiple small files is always burdensome on LANs. The MicroServer’s results were more promising this time around but it was still consistently slower than the other two PCs, albeit by a small margin.


These recordings were made with a high resolution, lab quality, digital recording
system inside SPCR’s own 11 dBA ambient anechoic chamber, then converted to
LAME 128kbps encoded MP3s. We’ve listened long and hard to ensure there is no
audible degradation from the original WAV files to these MP3s. They represent
a quick snapshot of what we heard during the review.

Each recording starts with ambient noise, then 5~10 second segments of product
at various states. For the most realistic results,
set the volume so that the starting ambient level is just barely audible, then
don’t change the volume setting again while comparing all the sound files.


The HP ProLiant MicroServer Gen8 is a big improvement over its predecessor in several ways. Switching to a slim optical drive and retooling the internal design has made the new enclosure even smaller. The rat’s nest of wires inside the original system is nowhere to be found — the interior has been decluttered with all the cables consolidated, leaving a very clean layout. Passive CPU cooling has been retained, even though the Gen8 is much faster. The new MicroServer runs circles around its predecessor, as it is a benefactor of significant gains in processor technology over the past three years. Though not strong performers in modern terms, the Ivy Bridge chips offered by HP are still quite capable and run fairly cool.

The choice of 35W CPUs unfortunately makes it less energy efficient (the first
MicroServer used a 12W Athlon II Neo N36L), bumping up the idle power consumption
by about 10W. While not as frugal, it is certainly within reason and comparable
to a typical DIY Sandy/Ivy Bridge desktop build when idling. The new version
is also a lot louder than the original… unless you run the native storage
controller in RAID mode. (See Mike’s notes below.) If you’re looking for a customizable
quiet solution, it’s not ideal due to the lack of user fan control, and the
fan’s surprisingly stubborn resistance to modification. Not in RAID mode, the
MicroServer is best buried in a closet or tucked under a desk where noise level
isn’t a priority.

HP’s iLO (Integrated Lights-Out) system allows users to manage the server remotely but unfortunately, out-of-the-box, access to the remote console is severely limited if you decline to purchase a supplemental iLO license. HP has added RAID 10 support in addition to RAID 0/1, but RAID 5 isn’t available without upgrading the drive controller, and hotswapping is still not supported. A second ethernet adapter has also been included, which can be useful for balancing high levels of server traffic. The Gen8 is faster and sleeker and gained a few useful features but it’s still far from a complete solution.

For sophisticated home users thinking that the Gen8 could double as a HTPC or network video player, hardware limitations prevent this. Not only is there no HDMI or onboard audio, the board’s server chipset doesn’t support Intel’s processor graphics so HP equipped it with a rudimentary Matrox GPU which can’t even output 24-bit color at a decent resolution, let alone accelerate HD video. It can serve up media just fine but it can’t really play anything on its own, at least not straight out-of-the-box.

While the Gen8 is a much needed update to an aging SKU, our overall opinion of the MicroServer remains mostly unchanged. It’s certainly a compelling product, much more so now after this recent facelift, but it doesn’t necessarily make sense for every home or small business. Cookie-cutter solutions like the NAS server boxes offered by QNAP and Synology aren’t as fast or flexible, but they do have RAID 5 and hotswappable drives which are big selling points. They’re also easy to use and manage — it’s very much a no-fuss, no-muss experience which can be advantageous for smaller operations that don’t have the luxury of a dedicated IT support staff. The Gen8 is really for those with the skill and knowledge to customize a server for specific needs and for whom a full-blown blade or rackmount server is overkill or simply takes up too much space.

The MicroServer Gen8 is priced at about US$449/US$529 for the
basic Celeron G1620T/Pentium G2020T variants with 2GB of RAM, fairly reasonable
considering there’s nothing else quite like it on the market, making it a niche
product. The MS Server 2012 included version with a G2020T, 4GB of RAM, and
1TB of storage doesn’t seem worth it at US$939— you’ll save
quite a bit by purchasing a base model, upgrading it yourself and going with
an open source OS.

EDITOR"S NOTES: Microserver Gen 8 Fan Control, Acoustics &

Two Step Forward… and one step back. The original Microserver
was a huge hit because it combined small size, high space and energy efficiency,
good enough performance, and low noise straight out of
the box. The relatively simple mods we devised to reduce the noise further
was icing on the cake. Our fan modding addendum, with details of the non-standard
4-pin PWM wire coding used by HP, probably helped sell a lot of Microservers,
especially to technical consumers for use as media servers in homes.

The new Gen8’s intractable fail-safe fan/thermal shutoff system is draconian.
Any attempt to slow the fan, even applying a little friction by hand on
the fan’s hub, is enough to trigger a complete system shutdown. There
is no hardware monitoring or fan control section in the BIOS; all this
is relegated to HP’s vaunted ILO system, which as Larry pointed out, costs
more money.

Could the fan be replaced with a quieter one? The 6-pin, 5-wire fan is
so far from standard PWM fan configuration that even finding a plug to
fit the six tightly spaced pins was a challenge. After much scrounging
in the lab’s old parts bins, I adapted an old 4-pin cable for audio directly
from a CD drive to the motherboard. The cable was cut in two and both
ends used with pins reconfigured so they made contact with the relevant
five pins on the motherboard fan header. The cut ends of the wire were
bared and tinned so they could be poked into the 4-pin female connector
of a standard PWM fan. Two of the wires from the stock fan are black,
so it seemed safe to assume they were both ground, which left 4 wires
to play with. I experimented with several PWM fans and umpteen combinations
of terminations, to no avail. No matter what I tried, the fans would 1)
not start, which led to the Gen8 shutting down before the end of the boot
sequence, 2) start at full speed, or 3) start at reduced speed but then
get into an annoying speed up/down cycle once in the OS and within a few
minutes result in a forced shortdown. After a couple of days of this,
I gave up.

The discussion thread "MicroServer
Gen8 is noisy
" in HP’s own forums started 08-15-2013 has 134
posts and remains active today, even though it was marked as "solved"
(by a HP mod?) on 12-04-2013. The problem is described thus:

If using AHCI or Legacy controller mode, fan noise will occur.
There is no possibility in lowering the fan speeds in this modes to
a lower value. It is going to be BIOS/iLO safe ranges.

The solution is "to configure the B120i in RAID mode. That
would mean configuring at least one disk as a RAID-0 array
The end result, reportedly, is that the fan speed drops from about 37~39%
to 22%.

Never mind why fan control is tied to the storage controller.

The procedure to run RAID requires switching the B120i built-in storage
controller in Gen8 to RAID mode, then installing the RAID driver once
you boot into the OS from another drive. For those accustomed to the user-friendly
BIOS of consumer boards, this seemingly simple procedure in Gen8 is absurdly
complex, perhaps to chide you for not obtaining some server tech certification?
Getting the storage controller into RAID mode did indeed drop the fan
speed immediately to a lower speed, a little under 1200rpm as measured
with our calibrated strobe . It improved the overall noise quite significantly,
to a measured 19 dBA@1m SPL. With our standard four drive array in place,
the overall SPL was just over 20 dBA@1m, which is actually a bit better
than the original Microserver.

I did not repeat all of the thermal testing run by Larry, but tried some
load testing and noted minor increases in temperature on all the various
devices during routine use, no more than +5°C. Prime95 was run for
about 10-15 minutes, during which time, a bit of fan ramp up was noted;
when CPU temperature stabilized, the CPU was at 56°C (10°C higher
than during Larry’s testing) and SPL was just under 21 dBA@1m.

The overall noise reduction in RAID mode compared to ACHI is around 10
dBA, or roughly half the subjective noise.

If you have no wish to run hardware RAID (whether because you prefer
one of the Linux distributions with its own file management system, or
you prefer leaving the drives as individual volumes) then running one
drive as RAID 0 is a viable option, though it can increase complexity.
The drop in fan speed and noise is most definitely worthwhile if you are
a SPCR enthusiast… or even if you just want your server to be reasonably
quiet without burying the box deep in a big closet.

Still, the absence of user-configurable fan control, the absurdly complex
5-wire fan, and lower fan speed being available only in RAID mode are
all strange annoyances. As one HP forum member posted on on 01-16-2014,

… because the old Microserver did not have iLO functionality,
it was able to regulate the fans (by measuring system and disk temperatures)
and now that the system has built in iLO functionality this ability
has been lost for non i120 controlled system usage?

I am sorry if I am asking uncomfortable questions, all I want
is that HP take this issue seriously and try to resolve the noise issue
in a way that satisfies cosumers who have come to expect and enjoy the
silent operation from previous HP proliant microservers.

As I said in a previous post, the biggest selling argument and
the reason I bought a new microserver is/was its silent operation as
it is meant to operate in a silent environment.

Our thanks to HP
for the ProLiant MicroServer Gen8 sample.

HP ProLiant MicroServer Gen8 is Cautiously Recommended by SPCR
(only when run in native RAID mode)

(7 Oct 2014): Using a Standard 4-Pin PWM Fan in the HP Microserver Gen8

* * *

Articles of Related Interest
Seagate NAS HDD 4TB
Fractal Design Node 304 Mini-ITX Case
Chenbro SR30169 Mini-ITX Server Chassis
Gigabyte GA-H77TN Thin Mini-ITX Motherboard
Western Digital Red 4TB & Se 4TB Hard Drives
HP Proliant MicroServer

* * *

this article in the SPCR Forums.

Using a Standard 4-Pin PWM Fan in the HP Microserver Gen8

The big flaw in the Gen 8 Microserver is the choice of sole system cooling
fan, a 120mm Delta fan rated 3400 RPM (as far as we know) at 0.8A at 12VDC.
This fan is impossibly noisy at full speed (rated at 46.5 dB by Delta) and even
though its speed is thermally controlled, it keeps the new Microserver always
a few decibels noisier than the earlier Athlon II Neo N36L based machine. Because
the fan connects via 5-wires to an odd 6-pin header on the motherboard, we could
not replace the stock fan with a quieter one.

Some time after the review was posted, I received an email from a HP Microserver
Gen 8 user who had come up with a way to use a quieter 4-pin PWM fan in place
of the noisy stock 6-pin fan. Mihai Tianu sent me this link
on "Faking the Fan Signal" at the forums of homeserver.com
he first posted his findings.

When I asked him to write up his method as a postscript for our review, Mihai
Tianu asked that I distill his forum postings for SPCR audiences, as English
is not his native tongue. Here’s then, is my distillation.

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The fan in the HP Microserver Gen8 has a Rotational Detect (RD) tachometer
signal. What that means is that it doesn’t output pulses like ordinary PWM
fans, but just a low voltage (0.12V measured) when the fan spins. Shown below
is a technical description of this type of fan.

Technical details of RD tachometer signal fan

HP Microserver Gen 8 fan pinout key

You can trick the Microserver into "seeing" an ordinary 4-pin PWM
fan by connecting the Rotation Detect/Tachometer pin to the ground, and SHORT
CIRCUIT THE GROUND pins from the fan connector. See the diagram below.

How to connect a 4-pin WPM fan to the HP MS Gen 8 6-pin header

Personally I’d go replacing the FAN with a silent one which has ~75% of the
original fan’s airflow. I don’t use the server for heavy tasks and I think
it will be enough. Whatever you do, pay attention and leave the thermal protection
enabled in the BIOS.

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Our HP Microserver Gen 8 system had long been dismantled and stored
away. We didn’t feel confident about posting the above fan swap mod until we
tried it ourselves. That was finally done in the past 48 hours. The biggest
challenges are finding a connector to fit the tight 6-pin fan header on the
Microserver motherboard, and a PWM fan of the appropriate rated speed.

You may recall from the notes on page 8 of the original review
that I used an old 4-pin cable for audio from a CD drive to the motherboard.
The cable was cut in two and both ends used with pins reconfigured so they made
contact with the relevant five pins on the motherboard fan header. This time,
the cut ends of the wire were bared and soldered to a male 4-pin fan header.

I reached for the first reasonably suitable PWN fan on our shelf,
which was the stock
sleeve bearing PWM fan of the Silverstone Argon AR01/AR03 heatsinks
. This
fan is rated for 2200 RPM and 0.23A. That’s about 1/3 lower RPM than the stock

I can report that this method of hooking up a 4-pin PWM fan to
the Microserver Gen 8 definitely works with Silverstone’s much nicer sounding
fan. The minimum noise level of the system dropped to about 20 dBA@1m, with
a smoother, less tonal sound quality. Many other PWM fans could have been used;
any PWM with good sound quality and 2000~2300 RPM rated speed should work well.

Even slower rated fans will work without triggering the MS Gen8’s
draconian fail-safe system. A Scythe
SL1225SL 12LM-P
fan , which we’ve measured at 1300 RPM top speed ran at
just 700 RPM hooked up this way in the MS Gen8, making almost no noise at all
(around 12 dBA@1m). This is not recommended, however, as your are likely risking
the thermal safety of the components with such low airflow. Besides, the little
fan in the power supply makes considerably more noise, so there’s no aural advantage
in running the main fan this slow.

So there you have it: A way to run your HP Microserver Gen 8 much
quieter than stock without having to run in RAID mode, with a much nicer sound
fan. The mod is relatively simple, the cost just the price of a good medium
speed PWM fan. Thank you, Mihai Tianu!

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this article in the SPCR Forums

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