Memory Channel Scaling with Sandy Bridge-E - A Core i7-3960X Experience


Roundup and Conclusion

Omission of Remaining Benchmark Results

We have excluded the results from the remaining benchmarks. They are as follows:-

  • 3ds Max 8 (SP2)
  • Cinebench 11.5 (64-bit)
  • Handbrake 0.9.4
  • Futuremark 3DMark Vantage (ver 1.03.1)
  • Far Cry 2
  • Battlefield Bad Company 2

Unlike in SYSmark and PCMark Vantage, there wasn't evident impact in these benchmarks when there was an increase of memory bandwidth or when running the memory at different frequencies. We have also excluded results pertaining to power consumption as the numbers were erratic and did not point to any conclusive results.

 

Conclusion

From the test scores of SYSmark and Lightwave 3D, it seems that by varying the memory bandwidth from 51.2GB/s to 21.2GB/s does not have much impact on 3D modelling tests. The only notable improvement (of about 7%) was found in the Video Creation scores of SYSmark when we scaled progressively from dual-channel to quad-channel mode. We also tried running quad-channel mode at 1333MHz and found that it scored lower than the triple-channel mode configuration at 1600MHz. This further  shows that the video creation tasks scale with memory bandwidth availability. Overall, it seems that by throwing more memory modules at an SB-E rig may not necessarily speed up the system and you could better utilize your budget on other components depending on what you intend to do with this extreme platform.

We recall speaking to Mr. Hunter Lee, Product Manager from Gigabyte Technology, at a recent Gigabyte X79 media showcase where he said that installing four identical memory modules into four DIMM slots is the sweet spot for memory configuration in a quad-channel memory architecture. Any more installed memory modules above this optimal configuration may result in memory timing issues and will slow down the system. Only extreme power users would benefit from extreme amounts of memory and this would only pay off when running very huge workloads.

From our testing, it seems that if we deviate from this 'sweet spot', the test rig's performance is not adversely affected even if we decrease the number of operating memory channels. In fact, with less memory channels operating, overclockers can better tweak their system performance to extreme limits. We feel that investing in a new set of quad-channel memory kits for your new SB-E rig is only worthwhile for computing performance purists who pursue only the best without compromise. Holding back the purchase of such kits is justified and scouring for a pair of appropriately rated; in terms of voltage (less than or equal to 1.5V), similar rated frequency DDR3 memory modules and the same memory capacity, to complement your newly purchased Intel X79 platform is a viable option.

As shown in our original review of the Core i7-3960X, we strongly believe that the Intel Sandy Bridge-E and Intel X79 platform is to address the enthusiast home workstation market segments. This follow-up article only further reinforces that fact as only power users who dabble solely in 3D, graphics or video content creation tasks and extreme video encoding workloads need apply. For all others, the standard Sandy Bridge platform (Intel Z68 and LGA1156 processors) is more than sufficient to meet most needs. The third and fourth memory channels of the Sandy Bridge-E don't benefit from standard workloads and most daily needs; it was meant for extreme workstation workloads.