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Intel’s LGA1156 and Lynnfield core

To be a fitting successor to LGA775, Intel’s new LGA1156 will have to offer a fair increase in performance and energy efficiency, but not so much to overshadow LGA1366. Lynnfield takes mostly after Nehalem, but requires only a single chipset (the new Platform Controller Hub), has a dual channel memory controller rather than triple, and uses a more aggressive form of Turbo Boost. Our first detailed look at LGA1156.

September 7, 2009 by Lawrence Lee

Product Intel Core i7-870
LGA1156 Processor
Intel Core i5-750
LGA1156 Processor
Manufacturer Intel Intel
MSRP US$555 US$199

Intel’s LGA775 socket started off in 2004 as a pariah for most
PC hardware enthusiasts. Back then Intel was still knee-deep in its Netburst
CPU architecture with Pentium 4s based on the hot, inefficient Prescott
core. At about the same time, AMD launched Athlon 64. which was greeted
with rave reviews and catapulted AMD ahead of Intel, but not just for a brief
stretch. In a stunning turn of events, AMD, the perpetual underdog, would go
on to push and stay ahead of Intel in performance and value for an unprecedented
two years.

In 2006. however, Intel struck back, dumping Netburst and emerging
to retake the performance crown with the Core and Core 2 architectures. The new
processors retained the same LGA775 packaging, though in reality Core 2 required
new chipsets and motherboards. Still, Intel had acquitted itself nicely and
LGA775 will likely be thought of favorably in the future. Unfortunately all
bad-turned-good things must eventually come to an end — the new LGA1156
socket now takes its place as Intel’s value desktop platform, the Robin to LGA1366’s
Batman.


Simplified chipset block diagram. LGA775 on the left, LGA1156 on the right.


P55 Express chipset: block diagram. P55 provides all the usual goodies
including a whopping 14 USB ports and 8 PCI Express 1x lanes.

LGA1366 represented a big upgrade in Intel’s core architecture. Nehalem
processors
brought small changes like the reintroduction of Hyper-threading
and a little free overclocking via Turbo Boost, but also drastic improvements
including the addition of an integrated memory controller and the fast QPI interface
connecting the controller to the Northbridge. The new LGA1156 processor, codenamed
Lynnfield, takes mostly after Nehalem, but is designed to function with only
one chipset. Lynnfield houses an integrated PCI Express controller, while the
rest of the Northbridge’s duties has been combined with those of the Southbridge
into a single chip: the Platform Controller Hub. The PCH is connected to the
processor via a DMI interface rather than QPI. Taking out a middleman is always
good for efficiency. Lynnfield also lacks a triple channel memory controller
— LGA1156 users must settle for dual.


Our Core i7-870 engineering sample.

LGA1156 processors will be branded Core i3, i5, and i7 depending on the number
of cores, clock speeds, and features. The first Lynnfield chips released are
the Core i7-870, i7-860, and i5-750, clocked at 2.93, 2.80, and 2.66 GHz respectively.
They all have the same amount of cache and 95W thermal envelope, but the
i5’s are not equipped with hyper-threading, so the operating system can use
a maximum of 4 threads rather than 8. i5 also lacks the VT-d feature which
gives virtual machines the ability to directly access peripherals on their host.
Turbo Boost has been ramped up as well. i5 clock speeds can be boosted an additional
533 MHz while i7 gets a maximum bump of 667 MHz.

Comparison Table: High-end Quad Core Desktop Processors
(09/2009)
Platform
Model
Clock Speed
Total L2 Cache
Total L3 Cache
TDP
Street Price
LGA1366
i7-975 EE
3.33 GHz
1MB
8MB
130W
$1000
i7-950
3.06 GHz
$570
i7-920
2.66 GHz
$280
LGA1156
i7-870
2.93 GHz
1MB
8MB
95W
$555*
i7-860
2.80 GHz
$285*
i5-750
2.66 GHz
$199*
LGA775
QX9775
3.20 GHz
12MB
N/A
136W
$1550
Q9650
3.00 GHz
95W
$320
Q9550
2.83 GHz
$220
AM3
X4 965 BE
3.40 GHz
2MB
6MB
140W
$245
X4 955 BE
3.20 GHz
125W
$195
X4 945
3.00 GHz
125W
$170
* boxed price (1000 units)

At the $200 level, the i5-750 is set to compete directly with the Core
2 Quad Q9550
and Phenom II
X4 955 BE
. The i7-870’s lofty price puts it in contention with the Nehalem
based i7-950, though it’s 133 MHz slower. Unless Lynnfield turns out to be superior
to Nehalem clock-for-clock, LGA1156 motherboards will have be a fair bit cheaper
to make the i7-870 a worthwhile purchase.


CPU-Z screenshot: Core i7-870.

Our Core i7-870 sample runs at 1.088V according the CPU-Z, which correlates
to a BIOS setting of 1.1375V. Our i5-750 sample reads 1.200V which is the equivalent
of 1.1625V in the BIOS.


CPU-Z screenshot:Core i5-750.

TEST MOTHERBOARD & HEATSINK

The P55 motherboard provided by Intel is an engineering sample, but likely identical to the model that will be released for sale, expect perhaps for the usual BIOS tweaks.


Our test motherboard, the Intel DP55KG utilizes the new P55 Express chipset.
The board looks a bit bare due to the presence of only one chipset, and
the lack of floppy and IDE connectors. A boon for gamers: the chipset
supports both ATI’s CrossFire and Nvidia’s SLI technologies.

 


The CPU latching mechanism is the recipient of a slight retrofit — with
a more pronounced hook at the end, the latch is unlikely to lose its grips.
The heatsink mounting holes are 75 mm apart, a bit less than LGA1366,
but a bit more than LGA775.

 


The back ports on the DP55KG are legacy-free. One interesting feature
is the “back-to-BIOS” button which lights up crimson red when
engaged. If you enter BIOS settings that does not allow it to POST, depressing
the button will allow you to make adjustments without having to clear
the CMOS.

 


Intel provided us with a Lynnfield stock cooler — a low-profile model
with a copper core similar to those that ship with most 45 nm Core 2 Quads.
We opted instead to use MUX-120 sent to us by Thermalright. It’s a a thin,
four heatpipe cooler like the original Ultra-120. Unlike most of Thermalright
heatsinks, it uses a pushpin mount.

TEST METHODOLOGY

Common Test Platform:

Intel LGA1366:

Intel LGA1156:

  • Intel Core i7-870 processor – 2.93 GHz, 45nm, 95W
  • Intel Core i5-750 processor – 2.66 GHz, 45nm, 95W
  • Thermalright MUX-120 CPU cooler
  • Intel DP55KG motherboard – P55 chipset
  • Corsair
    XMS3
    memory 2x2GB, DDR3-1600 @ 1333MHz, 9-9-9-24


LGA1156 test system device listing.

Intel LGA775:

AMD AM3:

Measurement and Analysis Tools

  • CPU-Z
    to monitor CPU frequency and voltage.
  • CPUBurn
    processor stress software.
  • Prime95
    processor stress software.
  • Cyberlink
    PowerDVD
    to play H.264/VC-1/Blu-ray video.
  • Eset NOD32 as
    an anti-virus benchmark.
  • WinRAR as an
    archiving benchmark.
  • iTunes
    an audio encoding benchmark.
  • TMPGEnc
    Xpress
    as a video encoding benchmark.
  • PCMark05
    as a general system benchmark.
  • Seasonic
    Power Angel
    AC power meter, used to measure the power consumption
    of the system.
  • Custom-built, four-channel variable DC power supply, used to power
    and regulate the CPU fan.

Benchmark Test Details

  • Eset NOD32: In-depth virus scan of a folder containing 32 files of
    varying size with many of them being file RAR and ZIP archives.
  • WinRAR: Archive creation with a folder containing 68 files of varying
    size (less than 50MB).
  • iTunes: Conversion of an MP3 file to AAC.
  • TMPGEnc Xpress: Encoding a 1-minute long XVID AVI file to VC-1 (1280×720,
    30fps, 20mbps).

Our testing procedure is designed to determine the overall system AC power consumption
at various states. To stress CPUs we
used Prime95 (large FFTs setting) or CPUBurn (which ever one produced the higher power
draw). We also performed a short series of benchmarks featuring real-world timed
tests and synthetics.

Cool’n’Quiet and/or Intel SpeedStep were enabled (unless otherwise noted).
The following features/services were disabled during testing to prevent spikes
in CPU/HDD usage that are typical of fresh Vista installations:

  • Windows Sidebar
  • Indexing
  • Superfetch

TEST RESULTS

Our test systems consist of 2x2GB of DDR3 memory (1333 MHz, 9-9-9-24-1T timings),
a GeForce 9400GT graphics card, WD VelociRaptor hard drive and an OEM Seasonic
power supply. Turbo Boost was disabled during testing — we consider it overclocking.
The ambient temperature was 21-22°C.

Test Results: General System Power Consumption (AC)
Test State
i7-965
i7-870
i5-750
QX9650
Q9550
X4 955
Idle
84W
54W
52W
68W
64W
73W
VC-1
Playback
100W
72W
72W
86W
75W
99W
CPU Load (half cores)
145W
104W
96W
122W
120W
157W
CPU Load (all cores)
203W
147W
130W
142W
140W
201W

The new Lynnfield processors impressed us immediately after general power consumption
tests. Compared to LGA775, the LGA1156 configurations used about 10W less less
power in idle and during VC-1 video playback, and approximately 20W less when
two of the four cores were stressed with Prime95. With wattage numbers in the low 50’s,
they rival some dual core processors in idle power draw. The Core 2 Quads were
already very energy efficient, and i7-870 and i5-750 proved to be even more
frugal.

The power draw of the two Lynnfields were similar — nothing but negligible
differences were noticed until the CPU was stressed heavily. With two cores working
at their maximum, the 870 used about 8W more. The difference more than doubled
to 17W when all four cores were taxed.

Undervolted Test Results: General System Power Consumption
(AC)
Test State
i7-870
i7-870
i5-750
i5-750
QX9650
Q9550
Stock
UV
Stock
UV
Idle
54W
53W
52W
48W
68W
64W
VC-1
Playback
72W
69W
72W
67W
86W
75W
CPU Load (half cores)
104W
94W
96W
85W
122W
120W
CPU Load (all cores)
147W
128W
130W
110W
142W
140W
i7-870 undervolted to 1.025V stable (~1.1375V stock).
i5-750 undervolted to 1.0625V stable (~1.1625V stock).

Undervolting yielded further gains in energy efficiency. We managed to get
the 870 semi-stable (10 minutes of Prime95) at stock speed with 1.025V in the
BIOS. The 750 required 1.0625V. This resulted in slightly less power draw
in idle and during VC-1 playback, saved 10W when two cores were stressed
with Prime95, and 20W with all four cores under load.


CPU screenshot: i7-870 undervolted to 1.025V. CPU-Z reported 0.768V when
idle (1.2 GHz).

CPU screenshot: i57-750 undervolted to 1.025V. CPU-Z reported 0.704V when
idle (1.2 GHz).

Performance

Benchmark Comparison
Test State
i7-965
i7-870
i5-750
QX9650
Q9550
X4 955
NOD32
2:02
2:15
2:31
2:23
2:31
2:27
WinRAR
2:16
2:28
2:38
2:51
2:59
3:05
iTunes
3:11
3:29
3:48
3:20
3:33
4:34
TMPGEnc
2:29
3:10
3:21
3:07
3:14
2:52
PCMark05
10502
8985
8390
9061
8760
9004

The 2.66 GHz i5-750 slightly outpaced the 2.83 GHz Q9550 in two of our timed
benchmarks, NOD32 and WinRAR. iTunes and TMPGEnc favored the Q9550, similar
margin. PCMark seemed to give the edge to the high-clocked processor, but for
all intents and purposes, the two are more or less equal in performance.

The 2.93 GHz i7-870 and 3.00 GHz QX9650 traded blows in a similar fashion.
The biggest difference between the LGA1156 and LGA775 processors seemed to be
in WinRAR, a very memory-dependent application. The lower latency and high bandwidth
provided by integrated memory controllers helped the Lynnfield CPUs take a large
lead in this particular test.

It would seem that these LGA1156 processors bridge the performance gap between
LGA1366 and LGA775, offering a nice performance boost over Core 2 Quads, but
falling short of the Bloomfield i7’s. In our most stressful test, video encoding
with TMPGEnc, the Core i7-965
EE
beat the i7-870 by 22% even though its clock speed was only 66 MHz
higher. AMD’s second fastest desktop processor, the Phenom
II X4 955 Black Edition
, is priced similarly to the i5-750 and depending
on the application, the i5-750 may be slightly faster.

Average/Total Benchmark Power Consumption

Average Benchmark Power Consumption
Benchmark
i7-965
i7-870
i5-750
QX9650
Q9550
X4 955
NOD32
111W
76W
75W
88W
84W
128W
WinRAR
108W
81W
79W
98W
96W
128W
iTunes
115W
78W
75W
92W
89W
137W
TMPGEnc
155W
108W
109W
118W
113W
167W
Total Benchmark Power Consumption (Watt-hours)
Benchmark
i7-965
i7-870
i5-750
QX9650
Q9550
X4 955
NOD32
3.76
2.85
3.15
3.50
3.52
5.23
WinRAR
4.08
3.33
3.47
4.66
4.77
6.58
iTunes
6.10
4.53
4.75
5.11
5.27
10.43
TMPGEnc
6.42
5.70
6.09
6.13
6.09
7.98

The total amount of power used during our timed benchmarks favored the Lynnfields
as well. In watt-hours used, the
i7-870 beat out the QX9650 by 15%, while the i5-750 bested the Q9550 by
11%. Both processors were also more efficient than the i7-965. As for the
X4 955 BE, well the numbers speak for themselves.

Underclocked Average/Total Benchmark Power Consumption

Average System Benchmark Power Consumption
Benchmark
i7-870
i7-870
i5-750
i5-750
Q9550
Q9550S
Stock
UV
Stock
UV
NOD32
76W
63W
75W
71W
84W
78W
WinRAR
81W
71W
79W
70W
96W
87W
iTunes
78W
75W
75W
73W
89W
81W
TMPGEnc
108W
91W
109W
95W
113W
102W
i7-870 undervolted to 1.025V stable (~1.1375V stock).
i5-750 undervolted to 1.0625V stable (~1.1625V stock).

 

Total System Benchmark Power Consumption (Watt-hours)
Benchmark
i7-870
i7-870
i5-750
i5-750
Q9550
Q9550S
Stock
UV
Stock
UV
NOD32
2.85
2.36
3.15
2.98
3.52
3.27
WinRAR
3.33
2.92
3.47
3.07
4.77
4.28
iTunes
4.53
4.35
4.75
4.62
5.27
4.79
TMPGEnc
5.70
4.80
6.09
5.30
6.09
5.53
i7-870 undervolted to 1.025V stable (~1.1375V stock).
i5-750 undervolted to 1.0625V stable (~1.1625V stock).

Undervolting shaved 12% off the total power used by the i7-870 during our timed
tests and 9% for the i5-750. Being able to run a stressful video encoding application
like TMPGEnc on a quad-core processor drawing less than 100W from the wall is
superb. Our i7-870 sample was the overall winner in efficiency. It had a fairly
low stock operating voltage and it also undervolted further than its lower-clocked
cousin.

Even at stock voltages, both Lynnfields edged out the Q9550S,
which has a TDP rating of 65W.

Thermals

Core Temperatures
Test State
i7-870
i5-750
Stock
UV
Stock
UV
Core 0
56°C
49°C
54°C
47°C
Core 1
50°C
43°C
49°C
43°C
Core 2
56°C
49°C
54°C
48°C
Core 3
50°C
44°C
46°C
40°C
Average
53°C
46°C
51°C
45°C
Thermalright MUX-120 with stock fan @ 5.6V (900 RPM).
Ambient temperature: 22°C.
i7-870 undervolted to 1.025V stable (~1.1375V stock).
i5-750 undervolted to 1.0625V stable (~1.1625V stock).

In our open testbed, cooled by a Thermalright MUX-120 heatsink using the stock
fan running at 900 RPM, the core temperatures (as reported by Core Temp and
SpeedFan) were fairly low. Both processors averaged in the low 50’s when placed
under full load with Prime95. Undervolting cooled temperatures by 6-7°C.
The heatsink barely felt warm during testing — it shouldn’t be difficult to
cool these processors quietly, but early adopters will have to wait for more
cooling options to be released.

Motherboard Impressions

Our Intel DP55KG was a pre-production sample using the latest BIOS provided
by Intel. It was quirky compared to most of the retail boards we’ve reviewed
in the past. At first we used regular Corsair XMS3 memory, but the board refused
to POST. We switched to XMS3 DHX, and it worked fine. After changing some minor
settings in the BIOS, it again failed to POST, and required a BIOS reset. When
we added a second stick of XMS3 DHX, the board again protested. In the end,
we used two sticks of XMS3, which worked with a voltage increase, however, they
would only function properly in the blue slots, not the black. Also, when we
switched processors (even though we set the CPU settings to Automatic), we had
to reset the BIOS once again. All in all, a rather frustrating experience. Luckily
there is an error code display directly on the PCB. Other than the above problems,
there were no stability issues and the board’s VRM and chipset heatsink stayed
lukewarm during testing.

The BIOS allowed for 3-pin and 4-pin control on three fan headers, though the
CPU fan header generated an odd buzzing noise when used with the Thermalright
MUX-120’s stock PWM fan (swapping the fan or header resolved this issue). Incidentally,
SpeedFan’s current version, 4.39, does not support this board. The frequency
and voltage options were liberal. You can change how much increase Turbo Boost
provides, and you can vary the resulting speed depending on how many cores are
in use. When you override the CPU voltage, you can leave SpeedStep on, so a
lower idle CPU voltage is achieved when undervolting. VDroop can also be adjusted
— the default setting is high which makes for lower power consumption.
For more stable overclocking, it should be set to low.

FINAL THOUGHTS

Despite some hassles with a quirky motherboard, our experience with the new
Lynnfield processors were mainly positive. They do not offer the kind of performance
increase that LGA1366 brought to the table, but they bridge the gap
between Core 2 Quads and the Bloomfield
i7
‘s. We were far more impressed with the energy efficiency of the i7-870 and i5-750 samples. Not only did they
use less power than their LGA775 counterparts, they even managed to beat out the
Q9550S, a high efficiency 65W part. As a
bonus, they also displayed some undervolting potential. Cooling a Lynnfield
processor should be a fairly trivial matter.

If you already have a fairly high speed quad core setup, there isn’t any reason
to jump ship to LGA1156. However, if you’re aching to upgrade from a single
or dual core system and energy efficiency is high on your wishlist, a Lynnfield
may be just what the doctor ordered. From a pure performance/price standpoint,
the i5-750 represents a solid value, giving stiff competition to the
similarly priced, but higher-clocked Intel Q9550 and AMD X4
955 BE
. The i7-870 on the other hand is LGA1156’s flagship, and as such,
is tagged with a heavy price premium. In most cases, the kind of money
the i7-870 commands is better spent on a cheaper CPU with the savings distributed
to other system components such as graphics cards and solid state drives.

CPU pricing is not the only thing to consider in regards to value — motherboards
and memory are the other main factors. Solid information about LGA1156 motherboards
is hard to come by with most rumors/speculation indicating a $100 price-point
at the low-end, and upwards of $300 at the high-end. The street price for memory
still favors DDR2 — 4GB of DDR3-1333 goes for $20 more than DDR2-800. Penny-pinchers
may consider an AM3 quad core paired with a AM2+ motherboard a more palatable
choice, especially if they’ve already invested in DDR2. A DDR2 powered Core
2 Quad system is somewhat less viable, given that LGA775 is nearing its end. In summary, LGA1156 looks like a natural and positive transition forward from 775.

Our thanks to Intel
and Thermalright
for the product samples used in this review.

* * *

Articles of Related Interest
AMD’s
785G Chipset Boards: 780G Evolved

Intel Q9550S: A Greener Quad Core?
AMD Phenom II X2 550 BE & Athlon
II X2 250

AMD Phenom II X4 955 Black Edition for
AM3

Phenom II: AMD pulls closer
Intel Core i7: Nehalem Launched

* * *

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