My DAW computer died. I took it to the local PC store, and the kid hooked up a handheld device with 4 LED's on it, fired up the PC and said "Your PSU is no good". It's a Thermaltake 600w (W0129RU). He put one off of the shelf in, fired it up and still no luck. He said, "You need a PSU with another connection.", so he put another one in, still no luck, then said "Your MB is shot too". He gave me an estimate to make everything right, but I just wasn't so sure about him.

It's a home assembled PC I bought from a guy on another forum. ASUS P5Wd2, Redeon X1900xt, M-Audio 1010lt, 2G, Western 250 HD. Windows XP Home, SP2 and I'm using Sonar 7 Producers Edition.

When I turn on the PC, all the fans fire up. When the PC was working, the video card fan would shut off after a few seconds.
Now, the video card fan just keeps running, and there is nothing showing on the monitor...except for a brief "No Signal" message. The little indicator lights on the front of the case stay lit.

I saw a thread here about using a multi meter to check the PSU, and I get 5.09v on the red and 12.05v on the yellow, there wasn't an orange wire that was easily accessible. When I turn the PC on, the PSU fan fires right up.

I replaced the battery on the MB.

I'm just wondering if the PSU could be bad, when it appears to be OK?
Is there something else to go wrong in a PSU, or was the kid at the store wrong?