Computer shutting itself off

[Devarian]

Alright, I tried to figure out what the problem is, but I don't know, so I'm asking you guys.

I can't remember when it first happened, just randomly while i was using my computer. I didn't see anything wrong so i turned it back on and it happened again after a few hours. I opened it up and tried to find something wrong, but I didn't see anything again. So i turned it on again to see if there was something that triggered it and it shut off just as windows tried to load. So I open it and unplugged everything and reset the bios, turned it on with everything still unplugged and loaded the bios, I was going through changing settings and after like a half hour it shut itself off again, while in the bios. I was mostly watching TV, so it just sat in the bios for a while.

I replaced the psu, same thing. Switched out the RAM, same thing. Each time the IDE and SATA cables were left unplugged, no power going to any of the drives. video card and sound card were still in the slots. Now when i try to start it up it'll start Windows and get to the login screen fine, but as soon as I login it shuts off, doesn't even get Windows up. At first I wondered if it was something with the hard drive, until it restarted in the bios without the hdd plugged in.

Anyone have any idea what it might be? I didn't change anything before it started happening. But the mobo and proc are about 8 years old, maybe they're finally just giving out.

Any input is greatly appreciated.

specs: (no mocking)
AMD Athlon a64 3700+
MSI K8N Neo4-F
OCZ 2gb pc3200
ATI Radeon HD 4650
Sound Blaster Audigy LE

and.. thats all I remember, WD hard drives, i actually tried to look up the hardware on my computer until i realized I'm using my laptop

 

[house70]

Is the heatsink/fan clean? I mean, is there any dust that can be seen in the heatsink's fins? It might be due to overheating and that can be caused by plenty of things, most commonly a heatsink that has been ignored (not cleaned) for a long time.
If not that, and you have just replaced the PSU, it could be the CPU that's finally on it's way out. Also, check the other side of the mobo for any possible dust/insects/whatnot that could cause a short. Remove the sound card and see if it happens again. You have already started an elimination process with the PSU and the RAM. Unfortunately, you can not boot without the CPU or the mobo, so if it comes down to any of these, you will need a new system. To replace those would not be cost-effective.

 

[Supermuncher85]

Sounds like a cpu thermal issue to me. Check that the CPU heatssink is working and attached correctly.

 

[T_T]

Also check the CPU thermal paste. After 8 years, it probably needs a new application of paste. Put some Artic Silver 5 on there. I would also try replacing the CMOS battery, its a CR2032 and can be found just about anywhere batteries are sold.

 

[55Range]

Yeah seems temps issue, check for dust as suggested, even in gpu, fans..
Monitor temps using HW monitor-

 

[Onus]

What is your PSU? Brand and model, not just wattage, please.
But yes, it sounds like heat. When you apply fresh thermal paste, as T_T suggested, remember that you must first clean off any old paste. I use 91% isopropyl alcohol for this task. It is inexpensive and readily available at pharmacies / drug stores / chemists (name depends on where you live!). I agree with house70 that there is no point in spending money to try to fix this system, as its mobo and CPU are sufficiently old as to be obsolete.

 

[Devarian]

yeah, i dont intend on trying to repair it if it turns out to be the mobo or psu, its not even cost effective anymore.

the last time i turned it on i had it on its side, after taking out the new psu to return it, when it turned off the heatsink wasn't even warm. i open it every once in a while and break out the canned air to blow it out, so the dust build up isnt bad and all the fans are working. i do still have some arctic silver floating around so ill try that just for shits and giggles.

i guess after that either the proc or mobo are fried. i tried to look over the mobo to find something that looked burned out but i didnt see anything. i'm not really surprised if that is the case though.

thanks for the input all, ill give updates after i change the thermal paste.

the psu is a 450w BFG, the new one was a thermaltake 650, which has already gone back to BB