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Lynnfield Memory Investigation

The other day, I was doing some snooping on some competitors' websites, and I found that most of them are shipping their mid-range and high-end systems with DDR3-1333 instead of DDR3-1600 or even something higher like DDR3-2000. We do all know that RAM prices are very high right now, but system builders like Falcon Northwest have never sacrificed performance for cost, so there must be something else to it. I looked around on the 'net, but I couldn't find anyone who had bench-marked the most common speeds of DDR3 with Lynnfield's new memory controller. Sure, we've got excellent pieces about Nehalem's memory controller, especially this one at Anandtech, but I couldn't come up with anything about Lynnfield. Would losing a full 64-bit channel require us to crank the megahertz, or would Lynnfield be even more efficient and do just fine with two channels of DDR3-1066? Well I took it upon myself to do the tests and see which would be the case.

First off, the particulars about the test setup:

  • CPU: Intel Core i7 860
  • Motherboard: Asus P7P55D
  • Memory: Corsair XMS2 2x2GB DDR3-1600 C8
  • Hard Drive: Western Digital 640GB Black Edition
  • Graphics: ATI Radeon 5850 (875 / 1250)

This is my actual workstation, complete with Antivirus, Windows Update and monitoring applications running, so I've set the margin of error for these tests around 2.0%. This should better represent real-life situations.

I decided to run the Core i7 at my standard 24/7 overclock of 3.7 GHz with a 168 MHz BClk, and then see how the different memory dividers affected performance. This gave me the following exact speeds to test with, although I'll use their JEDEC counterparts in the following discussion:

  • DDR3-1680 C8-8-8-24 2T
  • DDR3-1344 C8-8-8-24 2T
  • DDR3-1344 C7-7-7-18 1T
  • DDR3-1008 C8-8-8-24 2T
  • DDR3-1008 C7-7-7-18 1T

I also found that with relaxed memory timings, I was able to push the CPU up to 4.0 GHz with a 182 MHz BClk. This resulted in the following memory speed:

  • DDR3-1460 C8-8-8-24 1T

So on the following pages we'll see how DDR3 speed affects some of the most common applications.