We know that testing a power supply on a loaded system is not the very best way, but you can not overlook real world testing. Other sites have methods that use thousands of dollars in equipment to provide greater detail. However, we do have a trusty digital multimeter and OCCT. These sites and the method they use are a good means of determining how good a power supply is, but we feel showing you how it performs under real world conditions as it is just as valid a measure of its performance.
Motherboard: Gigabyte X58-UD5P
Processor: Intel Core i7 920 @ 4.0 @ 1.4v
Ram: OCZ Blade DDR3 PC12800 6GB Tri-Channel
Video Card: XFX HD 4770
HDD: Seagate 7200.11
Power: Thermaltake Tough Power XT 1000
Cooling: Coolermaster 212 Plus
OS: Windows 7 RC
Thermal compound: Tuniq TX
I tested the two power supplies on the same test bench and honestly I got some pretty interesting results from the two. We measured each of the rails and were totally puzzled by the results. The 600 watt model performed great on the 5v and 12v rails reading 4.93 and 12.22 with a load. The 3v read 3.24 which is okay but could be better.
And for the 850 watt model all the rails read well: 3.34, 4.99 and 11.87 with a load. But we honestly thought the 12v rail would read higher as the test equipment isn't really enough to push a 850 watt power supply. Be as it may, the numbers are still within the acceptable range.