Tesla H for a Fanless NUC

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Tesla H is one of a dozen fanless “heatsink” cases offered by Akasa. This one is for the Haswell NUC and can house two 2.5″ drives in a wider, sleeker design. Thermally, it’s a winner, too. Market pricing vis a vis NUC kits and boards is its real challenge.

Product TESLA H
Fanless NUC Case
Manufacturer Akasa
Street Price US$100~110

The NUC is now the only line of motherboards and "desktop PCs" offered
by Intel, and a handful of fanless aftermarket cases have appeared, taking advantage
of the NUC’s low power profile. Among the most prolific NUC case makers is Akasa,
whose first fanless case, the oddly named Euler,
was for Thin mini-ITX. The Euler was good enough, though a little rough around
the edges, and it helped Akasa gain some recognition among silent PC enthusiasts.
Akasa expanded its small fanless case range, and the Tesla H is one of a dozen
fanless case models Akasa is currently offering. There are three Tesla variants
to accommodate the different NUC models with varying back and front panel ports.

The Tesla is considerably bigger than standard Intel NUCs, understandbly as
it’s designed to fit two 2.5" drives. The case is a bit over twice as
wide, although shorter than Intel NUC cases designed to
house a 2.5" drive. But because the NUC board is so tiny to begin with,
just 4" x 4", the Tesla still occupies only about a litre of volume,
similar to the Thin mini-ITX Euler. Compared to the tall Intel NUC cases,
the Tesla’s proportions are more pleasing to the eye… and it is fanless. The
Tesla resembles the Logic
Supply ML300
, a fanless NUC case which can hold a single 2.5" drive.



It’s twice as wide as the standard Intel NUC cases.


A standard Intel NUC, not designed for 2.5" drives.



This is the style of the NUCs that hold a single 2.5" drive.

This particular model, Tesla H, is designed specifically for the Intel D54250WYB
and D3410WYB NUC boards, both of which have a single SATA port in addition to
the slot for a mSATA SSD. Two 2.5" drives can be fitted. The second
2.5" drive can only be used, however, if an optional mSATA to SATA adapter
is used.

Akasa Tesla H: Product Details
from the
product web page
Model No. A-NUC05-A1B
Material Aluminium
Motherboard UCFF 4" X 4"
Drive Bays 2 X 2.5" SSD/HDD (up
to 12.5mm high); second drive requires optional mSATA to SATA adapter (product
code: AK-PCCMSA-01)
Front I/O Port USB 3.0 port x 2, IR receiver
opening, HD Audio in/out
Security Kensington lock
Antenna fitting holes 3
Serial port opening 2
VESA mounting Supported
Net Weight 1200 g
Dimension 240 x 150 x 48mm (W x D
x H)
1.7 liters

The Tesla H comes with a slew of little plastic bags containing all the various
hardware to install the NUC board, and attach the casing/heatsink to the CPU.


The small 3-screw aluminum piece in the top center above is the CPU
heat block which clamps to the NUC CPU. It is a simple bridge between
the CPU and the top of the casing. Simple tension clamps the top finned
cover to the heat block. The blue/green blocks are soft gooey thermal
interface blocks to allow heat from the mSATA drive SSD to be conducted
to the casing. The larger rectangular aluminum pices are the sides of
the 2.5" drives sled. There is also a single-sheet
multilingual, mostly pictorial, mostly clear enough, assembly guide

(PDF document link to Akasa site) that managed to slip out of this photo.

SYSTEM ASSEMBLY

The biggest challenge in conducting this review was to find a suitable motherboard.
Yes, we had an Intel D54250WYK kit with the motherboard that this Tesla is meant
for, but it was being used in a long term project for a while. Intel was no
longer providing samples for reviewers, and while NUC kits are reaily available
from many vendors, the boards are much harder to find and priced pretty much
the same as the kits. An early attempt was made to remove the board from the
Intel D54250WYK case, then abandoned for fear of breaking the board; it is a
very tight fit. Recently, I worked up my nerve again, and managed to get the
board out after an hour of anxious fiddling and prying. Once the board was out,
assembly into the Akasa Tesla proved to be relatively painless.


The main parts of the Intel NUC kit, disassembled.


Stock heatsink & fan removed.


Some thermal interface goop (a little too much) on the bare CPU die, and
a small soft TIM pad on the video die.


Somehow, I missed a photo of the heat block mounted on the board, but
here’s the end result, with the board and CPU clamped to the casing top,
which happens when the board is screwed in place. The cables are mounted
exactly as shown in Akasa’s manual; there’s basically no other way to
run them.


This clever infrared remote extender is worth noting.


RAM and Kingston 120GB mSATA SSD installed.


WD Scorpio Blue 500GB .5" drive with side brackets mounted. Just
four screws, into the sides of the drive.


Everything in place. Note thermal blocks atop mSATA SSD.


The thermal blocks get mated to the bottom of the case for heat dissipation.


The feet get mounted to the VESA holes, which aren’t ideally positioned
as they’re far from the corners, but in actual use, they work fine.

UP & RUNNING

When powered up after the system was fully assembled, the blue power LED proved
too bright for my taste. Aside from that, the system ran without any glitches;
I was relieved that all my man-handling of the NUC board while getting it out of
the stock Intel case didn’t break anything.


Pictured here behind a small mouse and Audioengine A2 speakers, below
a large wall-mounted Samsung TV.

Time now to test the mettle — the thermal performance — of the Tesla
H.

The system components were the same as those for the Intel
Haswell NUC
review, with the addition of the WD Scorpio Blue 500GB 2.5"
drive.

Software and Measurement/Analysis Tools:

NOISE

The Intel NUCs have "the distinction of being the quietest fan-cooled
mini-computer(s) we’ve come across." Our highly sensitive acoustic test
system barely registered any rise in the ambient sound level in the anechoic
chamber when the NUCs were idling or playing HD video, at 0.6m from the unit.


This graphic is for the original Intel NUC kit; the Intel Haswell D54250WYK
sounds the same.

Of course this applies only when the Intel NUC kits are in idle, modest or
nominal load. With the torture test loads, Prime95 and Furmark, the fan noise
jumped in both volume and pitch to a fairly loud 31 dBA at 0.6 meter, and it’s
a hissy and whiny noise.

With the fanless Akasa tesla H, you know there is no noise except for what
comes from the 2.5" drive. We measured that drive to be extremely quiet,
12 dBA@1m, which might go up a titch at 0.6m (which is the official "seated
user" distance in the Computer Noise standard ISO 7779). Inside the Tesla
H, it actually measured just 13 dBA@0.6m and was inaudible for me at about 1.5m.
When the drive was forced into a constant write state, the noise measured about
15 dBA@0.6m, and from about 2m distance it was effectively inaudible.

COOLING

In the Haswell NUC review, I found the CPU throttled in the Intel casing when
its temperature exceed 80°C, when Furmark was run for more than ~10 minutes.
Here’s a review of the results from that review.

Intel NUC D54250WYK Measurements
State
AC
Fan RPM
SPL @0.6m†
CPU
PCH
HD
Top Cover‡
Idle
6W
1800
11 dBA
39°C
38°C
33°C
39°C
x264 video
9W
2100
12 dBA
54°C
51°C
43°C
40°C
TMPGEnc
20W
2800
16 dBA
70°C
59°C
43°C
42°C
Prime95
26W
4200
21 dBA
80°C
60°C
30°C
43°C
Furmark*
40W
5800
30 dBA
82°C
63°C
30°C
44°C
P95+Furmark*
40W
5300
28 dBA
80°C
63°C
30°C
44°C
Ambient: 22°C, 10~11 dBA.
External temperature measured using an IR thermometer pointed
at the hottest portion of the external chassis
We measure SPL at 0.6m for all devices meant to be used
atop a desk, as it is more realistic a distance than the usual 1m. It
also corresponds to the "seated user SPL" distance as per the
computer noise measurement standard ISO 7779.
* Throttling occurs at a bit over 80°C. See text.

I expected the Tesla to be no worse, but not really better, judging by the
results obtained in the similar Logic Supply LGX ML300 Fanless NUC. See the
results from that review below. Note, however, that this system used a different
CPU with a TDP of 17W, slightly higher than the 15W spec’d for the chip on the
D54250WYB board.

Logic Supply ML300 Temperatures
State
AC
CPU
PCH
HD
Top Cover
Idle
6W
60°C
43°C
30°C
39°C
x264 video
9W
64°C
53°C
30°C
54°C
TMPGEnc
25W
81°C
59°C
30°C
63°C
Prime95
29W
90°C
60°C
30°C
64°C
Furmark
36W
90°C
63°C
30°C
66°C
P95+Furmark
38W
90°C
63°C
30°C
66°C
Ambient temperature: 22°C.

Surprisingly, there was a discrepancy with power draw in Prime95. For some
reason, the version of Prime95 used for the earlier Haswell NUC review did not
result in the same power load as before, even with the additional 2.5"
drive, being some 4-5W lower than in the original NUC kit review: 24~25W instead
of the 29W seen in the earlier NUC review.

In the end, the latest version of Prime95 was tried, and it gave a power result
a few watts higher than before: 31W instead of 29W. This was accepted, as there
seemed no way to duplicate the 29W observed earlier.

Despite the absence of a fan, the Tesla H kept the components a bit cooler
than in the stock Intel case, especially at lower loads, with the advantage
at high loads of emitting no noise other than what the WD drive produced.

Furmark still pushed the cores to above 80°C and caused some throttling,
as before. The most alarming temperature was that of the PCH, which reached
85°C after half an hour and likely not good for the unit’s health. SSD temps
also soared under Furmark. Note, however, that the ambient temperature was several
degrees higher than in previous test runs. The top casing did get pretty hot
to the touch under Furmark, but it cooled off reasonably after 10~15minutes
in idle.

Akasa Tesla H w/ components from Intel D54250WYK
kit & WD Scorpio 2.5" drive
State
AC
CPU
PCH
SSD
HD
Top Cover
Idle
7W
40°C
42°C
45°C
36°C
37°C
x264 video
10W
44°C
46°C
46°C
38°C
43°C
TMPGEnc
24W
68°C
58°C
49°C
43°C
49°C
Prime95
31W
78°C
73°C
62°C
53°C
56°C
Furmark
40W
80°C
85°C
69°C
54°C
62°C
Ambient temperature: 25°C.

There’s always some question of how relevant stress tests like Furmark or Prime95
are for practical usage. Normal users will never stress a system, especially
one like the NUC, to this load level. TMPGEnc, a video encoding program, is
about the most demanding program most likely to be used on one of these machines.
Under such load, the Tesla H just cruises.

A Cooling Tip: Akasa reps I met with at Computex 2014 in Taipei
last month said all of their fanless cases actually run cooler when mounted
vertically so that the fins run up/down, rather than flat as I’ve shown the
photos above. This is the same way that fins on power amplifiers, radiators
and other cooling devices are usually positioned.

CONCLUSIONS

The Akasa Tesla H does what it’s meant to do: Provide good cooling without
a fan and without adding any noise by itself for a NUC system equipped with
an additional 2.5" drive… or two. It is a classic "heatsink case",
built pretty efficiently around extruded aluminum parts. Not the prettiest or
most elegant of builds, but that hardly seems necessary.

At a hundred bucks a pop, though, the main question for potential buyers of
the Akasa Tesla H is whether its benefits justify the additional cost over a
standard Intel NUC kit with the same board. This is the same question one would
pose of the Logic Supply ML300 series cases, and any other fanless aftermarket
cases designed for the NUC boards. The Tesla H doesn’t add anything more in
functionality to the standard tall Intel NUC kit other than fanless, somewhat
cooler operation and the option to add a second 2.5" drive. The reality
is that the pricing of the kits and the boards is about the same, which means
the average buyers sees the Intel case & cooler & power brick as being
free. For example, at Amazon, the price of the Intel D54250WYB board used for
this review is $370; a BOXD54250WYKH1
kit
with the same board in an Intel NUC case that can fit a 2.5"
drive and a power adapter is priced lower, on sale for
$336. This might be an exception, but I haven’t personally seen prices for boards
that are substantially lower than for the kits. If you’re going to consider
spending $100 or more on a fanless NUC case, than you probably want to see the
board price be at least somewhat lower, say $50, than the kit.

All of this discussion is subject to the vagaries and variables of retail pricing;
Intel may have reasons to keep the kit pricing low, and who knows, you might
see the board prices drop once current kit stocks are depleted. I also haven’t
examined the pricing of the NUC boards and kits outside of the US and Canada.

Regardless, fanless NUC cases like the Tesla H don’t exactly stand in a great
market position in North America right now. From a purely functional persepective,
for a retail buyer, the Tesla H makes sense only if the system is going to be
under fairly high load much of the time, and positioned somewhere fairly close
to the users. As already discussed, the highest nominal software load we think
NUCs will face is video encoding, and that isn’t really much stress for the
stock Intel case, whose noise rose only to ~16 dBA@0.6m. At idle, it’s just
about silent. OK, toss in a 2.5" HDD and it might get a little hotter and
louder, say 18~20 dBA@0.6m. That’s still pretty modest, and if it’s VESA mounted,
the monitor itself will help block some of that noise. Put the machine in a
hot ambient environment, and the fan will ramp up quicker, louder. Hence the
big advantage in industrial or commercial applications where space is tight
and hot, and maintenance needs to be at zero. But for the average NUC user,
the Tesla H and its ilk looks like a tough sell, and this is especially true
for the
cheaper NUC Atom kits which start as low as $148

…except for those who value utter silence from their PC, never mind its size
or function. Say you equip your NUC with a 2.5" SSD as well as the mSATA
SSD to keep it absolutely silent. When that stock Intel fan ramps up, it will
annoy you. The Tesla H will never do that. This is the singular raison d’etre
of the Tesla H for the retail buyer. It will never make any noise while
keeping the NUC as cool or cooler than in the stock NUC case.

Thanks to Akasa
for the Tesla H sample.


Akasa Tesla H is Recommended by SPCR

* * *

Articles of Related Interest
Logic Supply LGX ML300 Fanless
NUC

Haswell comes to NUC
Akasa Euler Fanless
Thin ITX Case

Logic
Supply LGX AG150 Fanless Mini PC

Intel Next Unit of Computing Kit
DC3217BY

* * *

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