Boot problems

[luciddreams]

My Athlon 64 system used to work perfectly. Then a few days ago I started getting Machine_Check_Exception blue screens sometimes when I restarted Windows although UT2004, Prime95 diagnostic torture test, and all my other programs ran just fine then. Then, this morning the computer froze a couple seconds after loading Windows and getting to the desktop, but after restarting everything appeared to be okay, and I played UT2004 and did some web surfing and word processing just fine. However, a couple hours ago I got the Machine_Check_Exception blue screen not only when Windows shut down, but also when it was loading back up. It never manages to load Windows using the normal startup now, but Safe Mode seems to load to the desktop just fine. Just now, I ran memtest86+ for a couple hours without finding any errors. I installed Service Pack 2 a month or so ago and have had no problems with it until now.

I noticed that the +5V seems unusually low -- most of the time the BIOS reports it at 4.3V or so instead of its usual value of around 4.9V, although once it a while the PC health screen still shows it at 4.9V. As always the 5V standby is still reported at 4.99V though. All the other voltages also appear good. Both motherboard power connectors appear to be pushed all the way in.

Is it a power supply problem, a motherboard problem, a SP2 problem, or something else?

System specs:
Athlon 64 3000+
Epox 8KDA3J (250GB nForce3)
2x512MB Crucial Value CAS 2.5
NVIDIA 6800

 

[piroroadkill]

Check your mobo for bad caps, and if there are none that appear (bulging, leaking etc) then try a new PSU.

If there are bad caps then oh dear. You'll need to replace them or replace the mobo.

Weird though, it's fairly new system, but I'd check it anyway, that wavering 5v rail sounds a bit suspect.