Since we're on this topic, how can you tell the difference between a failing PSU and one that just doesn't have the juice for your hardware?
Heres my situation: (and this may help you out a bit too Meconium since I describe how I found my power problem)
I recently upgraded my PC with more memory and a new sound card. I was having stability issues that I initially blamed on Creative Sound blaster Drivers. After an hour or so of use, the system would become unstable, first by losing sound, freezing, etc. I tried a bunch of different drivers for the sound card until I finally gave up and went back to my onboard sound. I went into my bios to re-enable my onboard sound and noticed one of the voltage readings in the red. The 3.3V rail was at 2.9V.
I took my PSU voltage tester out and pluged it up, it read 3.36V. I pluged the PSU back into the motherboard, checked the bios and it was no longer in red... but it was low. 3.05V.
I reinstalled the sound card, and ran my computer while running Everest and monitored the 3.3V rail. At idle it was at 3.06. I did a stress test and it dropped slightly to 3.02. I ran that test for only about 15 minutes. I then just let it sit idle, checking every so often to see if the sound dropped like it had been doing. Finally I saw the voltage drop to 2.90 and when it did the sound went out. So there, I found my problem... it's power related.
So what does that mean? Is the power supply having issues or am I pushing it too hard? Heres my setup:
Antec TPQ-850 850W PSU
Asus P5E3 Delux Wi-fi
4GB Corsir DDR3
Intel Q6600 Quad Core
Two HIS Hightech ATI Radeon 2900XT 1GB DDR4 running in Crossfire
Sound Blaster X-fi Titanium Fatal1ty
Koolance INX720BK Watercooling Kit Cooling the processor and the two video cards
A few fans, black lights, Case has a LCD thingy on the front with temp readouts.
I've checked a few PSU calculators online but I recieved different info from the different sites. One said I needed around 750 Watts while another said I need close to 1000 Watts. Do I upgrade or do I RMA?