Considering one of the major selling points of this RAM is its ability to run at a low 1.35v, we were interested to see if that lower operating voltage translated into any savings in terms of power consumption.
In order to test this, we hooked up our trusty P3 Kill-a-Watt to our test system. Some people who are knowledgeable in this field may dispute the accuracy of readings from a Kill-a-Watt, but we think it should at least allow us to compare consistent results across our various memory modules. We compared our Corsair Vengeance LP review kit to the Corsair Vengeance 1600MHz kit that we reviewed previously, which runs at a stock voltage of 1.5v, and also a kit of Crucial Ballistix DDR3-2000 that runs at a voltage of 1.65v.
We tested under three different usage scenarios: (1) at idle at the Windows desktop, (2) running Folding@Home, which is a very CPU-heavy task that also uses a moderate amount of system RAM, and (3) running near 100% memory usage (8GB) using memtest. Our theory is that the variance in voltages will show up most prominently when a larger amount of system RAM is being used.
At idle, Windows task manager reports we are using 1.06GB of system RAM. While running Folding at Home, Windows reports 2.04GB are in use. For our memtest test, we ran three simultaneous instances of memtest, each using 2250MB of RAM for a total usage of approximately 8GB as measured in Windows.
The results of our test were very curious. According to our results, there are more factors that lead to overall system power consumption than simply DRAM voltage as set in the BIOS. The Crucial Ballistix kit, which runs at the highest operating voltage, actually demonstrated the lowest power usage at idle, 185W. The Vengeance LP kit resulted in a system draw of 187W, which was better than the Vengeance 1.5v kit, which pulled 192W, the highest in our testing.
As the system load increased, however, the lower voltage of the other kits began to manifest a power savings. Under Folding@Home, the Vengeance LP kit drew 1 watt less than the 1.65v Ballistix kit and 6 watts less than the 1.5v Vengeance kit.
Under memtest, our results were as we expected. The 1.65v Ballistix drew the most power, followed by the Vengeance 1.5v kit, with the Vengeance LP drawing only 286W. This translates into a savings of 12W and 9W, respectively. In an area with a relatively high cost of electricity, this could translate into a savings of about $1 per month, but only if the system was under heavy use 24/7.