I've recently upgraded my system and now when I try to recompile the kernel, or run graphic intensive applications, midway through, the power just shuts off.

Working config (before upgrade)
AMD AthlonXP 2000+
Biostar M7VIT Pro (KT400)
512MB DDR333
PNY Verto 5700 LE Optima
SB Live!
450W PSU

Upgraded components
P4 3.0 GHz (Prescott)
MSI neo2 (i865PE)

Two things come to mind

1) I have 2 256MB memory modules that are not the same brand, because I've recently installed a PNY module, the other module is Kingston VALUE RAM, it worked fine with the Athlon so I think I can rule this out.

2) I've checked my sensors and one that sticks out the most is my -12V running around -13.2V under a load, it usually runs around -12.6 which I still think is a little high.

I'd give some more output, but I'm in class now. I'm just looking for someone to give some insight, my best guess is the PSU needs an upgrading...

If I'm right about the PSU, any suggestions for a particular brand/wattage/etc. would be appreciated.

Thanks,
c4k

There might be an option in BIOS to shutdown PC when CPU temp passes a certain threshold.

I doubt it's a thermal problem considering my CPU temp stays at about 50 C...

[edit]
Just got home, I guess I was looking at the wrong thermal sensor, looks like it keels over at around 65 C...
[/edit]

Well, I threw a Thermaltake Pipe101 on it, using Arctic Silver 5 as the thermal compound... It runs at 38C idle and 48 C during a kernel compile... but it still crashes midway though the compile. just gets a little further than it did before... I also noticed after a crash that the PSU is really hot and smells like burning plastic... can't be good.

CPU temps in the 40's are reasonable, over 50 would be high IMO, and over 60 would be way too high. As for PSU's, I would say that in terms of wattage, a 450W PSU is pretty respectable and should be able to handle your listed components just fine. However, if it feels hot and smells like burning plastic, don't risk a fire. Get yourself down to your favorite computer store and replace that PSU immediately. Be sure to go with a name brand, such as Antec, rather than some generic no-name.

As a general rule, I would suggest a minimum of 350W-400W for any standard, modern PC with typical components; 400W-450W if you've got some extra components in there or a power-hungry video card; and 450W and up for loaded rigs with all the toys. That's just my rule of thumb, other people may have other recommendations. This PSU is the one I'm using in my main rig, and it's just great.

No matter what though, replace that power unit pronto. Seriously, don't run the risk of a house fire starting. -- J.W.

Just to let you all know, it definately was the power supply, I threw in an Enermax Noisetaker 485W, and just to make sure my problem was solved, I recompiled the kernel, ran multiple benchmarks via Quake 3 and Doom 3... no crashes, max system temp is ~32 C, max CPU temp was ~50 C