Diagnosing PSU issues

[Low Roller]

I'm pretty sure the PSU is the culprit in the PC I'm trying to fix, but I'd like to get some input here to make sure.

First, the system in question has been run at stock speeds and contains the components below:

Phenom II x4 955 BE
ASUS M4A785T
4GB OCZ 1600 DDR3
Sapphire 5850
WD 640GB hd
HP 22X DVD burner
Thermaltake TR2 W0388RU 600W PSU

The PC was assembled in January and worked flawlessly up until ~1 week ago. All of the sudden it became flakey as hell. Random BSOD's, reboots, freezes, you name it.

This past weekend I took to the task of trying to fix it. It boots into Windows fine(mostly), but not long after I start LinX, p95, or the Crysis benchmark it will reboot or BSOD. Once in a while it seems stable and fine, as it will complete 20 passes of LinX or finish the Crysis benchmark without error. But those are exceptions. Normally it will fail.

I tried the RAM and 5850 in my new i7 build and they work fine when installed in that machine.

After trying to run the system with a cheap PSU I had laying around without any better results, I pulled my Corsair HX750 from my new build(which was a real pain in the ass since I had zip-tied the heck out the wires), and swapped it into the system in question.

So far I'm on my fouth LinX run of 20 passes without any problems. I've got more testing to do but the PC is already leaps and bounds more stable than with the Corsair PSU compared to the Thermaltake. That much is evident.

I picked up a voltmeter today and will be testing it on the Thermaltake to see if I can detect any anomalies in the voltages. Not sure if I will since the PC seems to work ok when not stressed in any significant manner, but it can't hurt.


Is there anything else I should look for? How do I know if this isn't just the beginning stage of the mobo flaking out?