When it comes to testing a power supply, there are two courses to travel. One takes you down a path using a device to stress out the PSU and provide data regarding the power levels across all three rails. The second, and the one I make use of, utilizes an actual test system to give a more real-world account of what the power supply is capable of. While both methods have their merits, I prefer to use an actual computer to more closely resemble the manner of use that you, the potential customer, will put the product through.
That said, let's take a quick look at the test system. At the request of readers, I have beefed up the system to put a more realistic strain on the power supply.
Gigabyte 965P-DS4 motherboard (Supplied by Gigabyte)
Intel Core 2 Duo E6600 processor
2x 1024MB Corsair XMS2-8500-C5 memory (Supplied by Corsair)
GeCube X1900XTX graphics (Supplied by GeCube)
Sapphire X1900XT graphics (Supplied by Sapphire)
Western Digital 250GB SATA hard drive
2x Western Digital 160GB SATA hard drives
Western Digital 80GB hard drive
Sony 52x CD-ROM optical drive
Samsung 16x DVD-R optical drive
1x 200mm fan
2x 120mm fans
4x 80mm fans
While this isn't a Quad-GPU setup, we are certainly in the realm of having a system that is going to put a significant power drain on any power supply. Testing will consist of checking the power levels across all three rails at idle and again while the system is under stress. This should give us a good look at the capabilities of the power supply being tested.
When I first received this power supply, I had high hopes for its performance. After the dust has settled and the testing has been completed, it has done a good job of living up to the reputation Corsair has been making with their line of power supplies. Voltage levels across all three primary rails were above rated values and were still incredibly consistent. When a system is running it is common to see slight fluctuations on the voltage meter. Granted, these fluctuations are small and do not have any effect on system performance or stability, but they are generally there regardless.
This TX series PSU from Corsair had practically none. I say "practically" because I was able to note a flicker of 1/1000v on the 3.3v rail during testing, but this was all. Everything else is rock solid and totally stable. This is a very nice concept when you are building a power system that is going to be sucking the life out of a normal power supply.