PC will not stay on.

[jamesrizzle]

So I am trying to repair a Dell inspiron 531 with the AMD Sempron™ processor. It was brought to me because it was shutting down for no reason. I figured maybe it was dirty (over-heating) knowing it comes from a home with animals. So i opened it up and it was very dirty, I cleaned it without removing any components, powered it on and it stayed on long enough to boot up.....windows loaded.....then it just shuts off. All the fans are functioning well.So i removed the GPU, ram ect...cleaned them up and checked for damage...they appear fine, no burns, smells, or bubbled compositors.Same goes for the motherboard.
Now I re-assemble the machine, power it on and bam goes right back off...then it will turn back on, then off,on and off, until i disconnect the power cable. And it is passing the POST test. So i thought maybe it was the PSU, so i swapped it for a spare, that i know works, and still the same thing, on then back off. O.K I thought maybe Windows is corrupt or the hard drive is dying..so I tried to just boot to a repair disk, still just shuts off....and sometimes won't power up right away when i hit the power button. So I figured the only thing I have not removed was the CPU, so I removed the CPU cleaned it up and inspected for burnt pins..but the chip was pristine. But I did notice very, very light brown marks on the socket.I re-seated the heat-sink with fresh compound and mounted the fan....still, on, off. Now I am thinkin possibly the motherboard is toast, seeing how all of the components (with the exception of the CPU) Work outside of that box. I am puzzled, would appreciate any input.

 

[mti_32]

So I am trying to repair a Dell inspiron 531 with the AMD Sempron™ processor. It was brought to me because it was shutting down for no reason. I figured maybe it was dirty (over-heating) knowing it comes from a home with animals. So i opened it up and it was very dirty, I cleaned it without removing any components, powered it on and it stayed on long enough to boot up.....windows loaded.....then it just shuts off. All the fans are functioning well.So i removed the GPU, ram ect...cleaned them up and checked for damage...they appear fine, no burns, smells, or bubbled compositors.Same goes for the motherboard.
Now I re-assemble the machine, power it on and bam goes right back off...then it will turn back on, then off,on and off, until i disconnect the power cable. And it is passing the POST test. So i thought maybe it was the PSU, so i swapped it for a spare, that i know works, and still the same thing, on then back off. O.K I thought maybe Windows is corrupt or the hard drive is dying..so I tried to just boot to a repair disk, still just shuts off....and sometimes won't power up right away when i hit the power button. So I figured the only thing I have not removed was the CPU, so I removed the CPU cleaned it up and inspected for burnt pins..but the chip was pristine. But I did notice very, very light brown marks on the socket.I re-seated the heat-sink with fresh compound and mounted the fan....still, on, off. Now I am thinkin possibly the motherboard is toast, seeing how all of the components (with the exception of the CPU) Work outside of that box. I am puzzled, would appreciate any input.

ok how long does it take to shut down????1min -1hrs so on

 

[jamesrizzle]

Sometimes seconds...won't stay on for no more than a couple of minutes so.

 

[mti_32]

it sound like to me it could be the hard drive , lay the computer on its side and star it and see how long it says on and let me know

i got to take a shower so ill be up for 30min

 

[jamesrizzle]

It booted, but promptly shut down.....Could it be the hard drive, even though it won't stay on even in the setup utility...before windows tries to boot?

 

[user_account_]

I would say motherboard have you looked on the back of motherboard?

 

[jamesrizzle]

No did not remove the motherboard.....but will do..keep ya posted.

 

[jamesrizzle]

I pulled the Mobo out...the back looked fine...a bit dirty, but looked ok. But there is that little brown spot on the CPU socket............

 

[mti_32]

that cluld be the problem -

but also try booting it in bios and see if it crashes

ill be up for anther 25min

 

[jamesrizzle]

I tried booting to setup in bios. I can get in there, sometimes long enough to move around a bit, but soon followed by a crash. Booting to CD-ROM also crashes. Something is failing and I am suspecting it's not a peripheral device.

 

[mti_32]

it sound like a bad motherboard or cpu

going into bios by passes everything but video i beleve ,is the video card ok, is everything seated properly
have u tryed reseting the motherboard

 

[jamesrizzle]

The video card is fine but it will still shutdown using the stock integrated video as well. Everything is seated correctly (quadruple checked) and i even swapped all of the components(besides the CPU) into another box and they were fine.

 

[jamesrizzle]

I did not think about resetting the motherboard, will give it a try. But sometimes it stays on long enough for the BIOS to load.

 

[jamesrizzle]

So I took a gamble and bought a new motherboard (it was only 30$)....Installed it powered it up and it runs perfect, Windows loads...i let it run for about a half hour.....no problem. So I shut it down.....let it sit for a while....and what do you know it turns itself back on then shuts down. So I hit the power button and it is playing the same game again....on then off..wtf! So thinking maybe the processor is bad....or could the power switch cause this behavior?