Power Consumption & Overclocking Results

I decided to kick this off with the power consumption results. After all, this kit’s main selling point is the low operating voltage. These numbers were measured with a Kill-a-watt with a Core i7 860 operating at 160×19 for 3040MHz with 1.25vcpu, 1.30vtt, and the memory running at 1600MHz. EIST was enabled for additional power savings at idle. The 1.65v results were achieved with Corsair Dominator GT modules running the same settings but with 1.65vdimm. From what we can see the difference isn’t much but it was solid enough to document. The worst delta, 9 watts in 3DMark Vantage, is only a 3% power savings. However I imagine in a system where the memory forms a larger portion of the power budget, say a dual socket server with 128GB of memory, would see much larger savings. Progress is progress I suppose.

Since these are low voltage sticks I figured I should see some healthy frequency scaling with increases in voltages. This couldn’t be further from the truth. I originally planned on testing up to 1.65vdimm but when I didn’t see much in the way of scaling I went to 1.70 vdimm, 1.75vdimm, and even 1.80vdimm, a 33% boost in voltage. Turns out these sticks hardly scale with volts past 1.55vdimm. Rather, they scale by loosening the timings with a decent overclock to DDR-1900 achieved with 9-11-9-27 timings and 1.55vdimm. I suspect with further investigation whatever is holding the sticks back could be uncovered.

Update

Right before I wrapped this article up I decided to give the sticks one last go to try and break DDR3-2000. Turns out the sticks aren’t voltage limited but tRCD limited. Loosening the timings to 9-12-10-30 let the sticks pass at DDR3-2030, a modest 6% bump over the DDR3-1900 9-11-9-27. This was also with only 1.55vdimm, turns out more vdimm didn’t help stability.

Dropping to 10-13-10-30 let the sticks scale a bit more but Super Pi 32M was only stable past DDR3-2070 and the performance was terrible. That covers it for the overclocking with these sticks. Better off leaving them at stock and using them for their low voltage requirements.