I haven't gone through and tested each component on its own but with the following symptoms I'm almost certain its a faulty PSU.
- When turning the computer on for the first time in a couple days, it loads up to but not beyond the windows load screen before shutting down
- Subsequent attempts shut down sooner and sooner to the point where its only on for a split second
- The first time I tried booting up, I got it to the point where I could boot off a CD but again, after a few seconds, it just shuts down
- Also, no odd sounds or beeps to give more info on the problem
I'm tempted to say this is a PSU problem but that may be me not wanting to get a new mobo. Any help would be appreciated to narrow it down.
Sounds like it might be overheating. When you first boot it after it has been sitting for a couple hours try to get into BIOS and get to the screen to see your CPU temperature. See if it rises up and causes the system to shut off.