CPU: AMD Sempron 2500+ Socket A ( bought aug 2005)
MB: Gigabyte K8-Triton - GA-K8N5
Chipset: nForce 3 250
Ram: 2 sticks of 512mb DDR PC2700
Vid Card: BFG Gforce 5500FX oc 256 DDR
Hard Drives: Seagate 160 gig---30 gig Western Digital---20 gig western Digital
Power Supply: 500watts
OS: Windows XP Pro SP2
Sept 20th we had a power outtage for about an hour, PC was on. Went out of town for a month, came back turned PC on last night for the first time since power surge. It got to about 1 min booted to windows desktop, the CPU temp alarm went off, i was able to shut down. Restarted, CPU alarm, shutdown at windows boot screen.
Restarted, went into bios to watch the CPU temp. It went from 40 degrees c', to about 65 degrees c' before it shut itself down. I tried it a few more times with the same result. All fans were spinning and the CPU fan was running at close to 4000rpm in BIOS.
I removed the cover to find that it was molested by dust, cat hair, and dust bunnies from hell. Inside my case i have 7 fans. I attacked the inside with a can of air. I thought i saw something scurry away and realized it was a dust bunnie bigger then my cigarette butt. I removed the vid card and clean and lubed the fan. Removed 3 of the case fans and cleaned and lubbed them...got lazy with the remaining 4. I then removed the heatsink, used about 1 1/2 cans of air on it, then did the same to that fan. I then used some pointy tweezers to dig out some regenerating hairy dirt like slime, attatched to the heatsink cage. I noticed fur all around the edges of the processor. I didnt see any damage either. The thermal grease didnt look too bad. It wasnt burned, or dry. It was pasty, but not like it was when i first used it, and it was smmeary.
Put it all back together, booted up, it shut down as soon as the boot screen appeared. All fans were running.
Tried it 2 more times, once it shutdown at boot screen, second half way through windows desktop, i moved my mouse currsor while loading into windows desktop. Power supply fan was spinning.
Dunno what the hell...
Could new thermal paste be the problem?
Any replies could help.
Ok, first thing (even though i'm sure you've done it a couple times already) is to make absolutely certain the CPU heatsink is making a good contact with the CPU - as long as it is, you could even use chocolate as a thermal paste and it shouldn't get to shut-down temperatures (don't use chocolate =p )
If you're certain you've got good contact, the next thing to check is the CPU ... try it in another computer you or a friend have, and see if the problem exists there. If it does, it sounds like something inside the CPU fried (could even be something very simple like the temperature sensor which doesn't even effect how the chip runs).
If your CPU tests out fine, try the opposite ... source another CPU of the same socket type and try to use that one in your motherboard. If this reproduces the temperature error, then something on your motherboard is fried ... this time it could be from simple things like temperature diodes gone wrong, or it could be as bad as the motherboard trying to put an obscene amount of volts into the CPU - thus the heat and the shutting down.
I'm afraid neither of these two possibilities has a quick fix other than simply buying a new component - this should just help identify where the problem is.
When you remove a HS/Fan you should always replace the thermal paste. Using too much paste can also cause high temps. You can clean the old paste by scraping with a toothpick, or something plastic resembling a coin, flat screwdriver, etc. Just no metal. Any residual can be cleaned off with rubbing alcohol, and a soft paper towel.
After applying new paste, make sure the heat sink is fully seated and attached.
quintaar 
