CPU or Motherboard?

[RazB]

My PC shut off unattended yesterday. It did this every 2 weeks (I blamed my 4 yr old) or so but finally bit the bullit. When I try to power up , the fans turn on for a second and then shutdown. I unplug the power, wait 30 seconds...same thing. Also, there was a distinct burning odor when I opened the case but I couldn't see any obvious damage

I tried 3 power supplies with the same result. Weird thing is that when I remove the CPU, the case fans will run, but when I reseat...same as before, starts for a second and then shuts down. My instincts is the that the MB is bad since I get NO power when the CPU is inserted, but I'm confused as to why the fans work without the processor in.

Can a bad CPU prevent the entire MB from getting any juice to the other fans and components?

Setup - K7S5A, 1.4 Athlon, AIW Radeon, 768mb Crucual Memory, tried 300, 350 and 400Watt PSU

 

[Anubis]

either the CPU is dead or the mobo

 

[Ionizer86]

What kinda heatsink fan btw?

 

[RazB]

<What kinda heatsink fan btw? >

Ionizer,
I'm using the stock HSF (retail AMD)...as I stated before, the weird thing is if I take the CPU out, the case fans work. If I put even JUST the processor in, I get a half second start..then everything shuts down. I guess getting back to my original question, can a bad CPU make the whole motherboard act like it's dead or is the fact that the CPU is seated cause a short. I'm hoping that the problem is the MB since its an old K7S5A board.

 

[rainypickles]

i had a similar problem. my cpu was fine. it was the ram. i have no idea why a stick of ram could stop my machine from booting. test your ram; swap it.

 

[RazB]

Rainy...I don't think it's the RAM. The PC powers off completely within a second of pressing the power button. I guess I could try to see if the power comes on with the CPU and no memory to see if I get any beeps, but I doubt it'll get that far. To recap.

PC shut down completely, noticable burn odor
Must UN-plug power cable from case to re-boot
Re-boot dies INSTANTLY (1 second) and PC shuts off, no fans, no nothing.
Switched PSU, same result (2 different PSU's)
Removed CPU, case fans come on
Re-insert CPU, back to shutdown problem after 1 second

I guess I'm confused as to why a CPU would prevent the rest of the components from getting power unless there was a short in the MB that is by-passed when the processor is removed.

 

[Jojo7]

Do you think the cpu could be overheating and then the system shuts itself off? I'm guessing you've reseated the heatsink and it's on correctly.

Does the cpu core look ok? Not chipped or burnt or anything?

Is there any way you could try that cpu in another system?

It's really a tossup as to which part is the failing part (or possibly both went bad). Trying the cpu in another system would tell you for sure.

 

[RazB]

Jojo.....I guess I'll have to wait until Tuesday when Newegg delivers my new MB. I should've just ordered a CPU as well.... I hate giving our local PC shops any business because of their price gouging so I'm REALLY hoping it's the MB...Thanks Guys for trying!!!