Intel Xeon L5640

Tue, 24 Aug 2010 17:01:01 +0200

Introduction

Intel has recently updated its line of Xeon processors, and as such we present to you our test of some of the new low-power Xeons.

For our test we have a pair of Xeon L5640s. These are hexcore processors with a default clock speed of 2.2GHz, though this can rise to 2.5GHz if TurboBoost is active. The processors have a TDP of 60W each, which is just 10W per core, and are also fitted with Intel's HyperThreading technology, allowing each processor to present 12 cores to the OS (24 in total).

Test setup

Machines used in the test :

Our tests were performed on two different machines, as the SuperMicro board we used for the previous generation processors had a bug which meant it could not fully support the L5640's turbo mode.
The benchmarks were set by the following setups:

Dual Quad-core :
Supermicro x8DAi
2 Xeon X5560 ES (2.8 Ghz - 3.06 Ghz with Turbo mode)

Dual Hexcore :
EVGA SuperRecord 2
2 Xeon L5640 ES (2.2 Ghz - 2.5 Ghz with Turbo mode)

The other components in the test machine were the same for both systems:
6 x 2 GB Crucial ECC DDR3-1333
2 Noctua NH-U12P SE2
Nvidia 9800 GT
Windows 7 Professional 64-bit

Test methods:

The tests were carried out using one unit from project 6014 for standard SMP benchmarking and one unit from project 2685 for -bigadv benchmarking.
To measure power consumption, we used a watt meter manufactured by Watt&co. The values given are for total system power consumption, not just the CPUs. For Folding@home power consumption, only the SMP client was running.

Where possible, we will only give a single value for each WU type (currently sorted by how many points the relevant unit is worth). Measurements have been made using projects currently being assigned at the time of writing the article. For ease of use, all performance comparisons are given in PPD. The value we have used is the effective time per frame over the whole unit as measured by FahMon.
We use the site http://sites.google.com/site/mrjellyorg/folding-home/calculator to calculate the true PPD including bonus for SMP and bigadv units

The overclocked frequency of the L5640s was obtained with turbo mode enabled and a QPI of 195MHz. This resulted in a clock speed of 3.7GHz for the 12 cores with the boost from Turbo mode.

Folding@home performance (PPD)

The values are expressed in PPD (points per day)

Here we see a huge difference between the two systems. It is not surprising to see the overclocked L5640 has the performance advantage, but the performance gap is so large that the overclocked hexcore system is more than twice as fast when running standard SMP as the quadcore system was when running bigadv.

Power consumption

All readings are in Watts.

During the test with both machines at their standard settings the difference in consumption between them was only around 20 watts. The dual Quad predictably uses less energy but this is probably attributable to it having fewer cores and less cache than the dual Hexcore. The EVGA SR2 motherboard used for the hexcore also has more features requiring more power, for example an SLI controller chip (NF200), and USB3 and SATA 6Gbps controllers.

Energy efficiency (PPD/W)

All values are in PPD/W

We have recently seen graphics cards capable of 73 PPD/W (see the GT240 review). Here the efficiency may surprise some people: the dual Quad already reports very good results for energy efficiency but the dual L5640 takes it to a new level.
The most surprising result is for the overclocked L5640s. Even with energy consumption at the wall approaching 500W, performance has increased such that PPD/W actually increases with the overclock. In all cases the L5640 system is more efficient than any graphics card we have seen. This could of course change depending on any modification or cessation of the quick-return bonus system, or its extension to more client types.

Conclusion

With every new wave of processors we get new hopes for increased performance, better efficiency, etc. Quite often we are rewarded for our belief but occasionally our hopes are dashed. With the new Xeons, Intel has delivered in style, setting the benchmark for energy-efficient folding.

We have seen that the hype is backed up by the numbers, particularly when overclocked, and for that reason anyone looking to acquire a dual-processor Intel system is well advised to buy the EVGA SR2 as the heart of their system.
The initial investment may appear to be high but the performance has to be seen to be believed. We can only regret the seemingly random availability of the board in Europe.

The justification for paying so much upfront is the reduced outlay when your electricity supplier sends you the bill. Assuming continuous usage, each watt used for one year will cost about 1€. As a result the total operating costs for the overclocked system would come to around 500€ a year, which is extremely cheap for the performance available (though still not for the faint hearted )
One last note about the motherboard: we have already said that it is a must to unlock the true potential of Xeon processors, of this there can be no doubt. However the board will not be accessible to everyone as it is much more complicated to use and overclock than most motherboards. Part of the problem stems from the board's own heatsinks: any QPI baseclock higher than 200 will cause the system to overheat and crash. The use of waterblocks is thus almost mandatory for stable overclocks, though the performance we achieved in this test was done with air cooling only. A member of the site is trying the board out with waterblocks and a pair of X5560s, we will post a news when his tests are complete.

Finally, we must thank M. Moreau of Intel France who had the confidence in us to allow us to test Intel's hardware for you.

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