Computer restarts

Got a Compaq Presario 7000 that suddenly started to restart itself. When you power it up, it will run fine for about twenty minutes, then automatically restarts. No error messages or blue screen is presented, and it does'nt go through the actual "Windows is Shutting Down" routine, the screen just goes black and it begins to boot up. Though what happens is, when it begins rebooting, it won't even make it to the desktop before it starts to reboot again.

So I thought...must be over heating. I opened the case and blew all of the dust out. It has one large exhaust fan at the rear, which is working, and the PSU and CPU fans are both working.

The weird thing is, I can leave it sit for hours or even days, and when I try to power it on, it won't come on. If I mess with it for a while, pressing the power button continually, it will come on for about ten seconds and then shut off. So I'm now thinking maybe it's not overheating, since I doubt it could overheat within ten seconds.

So heres what I've done to troubleshoot...
Replaced PSU - no difference.
Removed every PCI card, left in HD, Optical drives (2), Video card and RAM (2 sticks) - no difference.
Removed HD, both RAM sticks and Video card - no difference.

So with nothing but the CPU, it still acts the same. I guess that rules out everything but the mobo and CPU right? I mean, a PC should boot and stay on with no RAM, HD or Video adapter.

So, it's not the PSU, not the RAM, not the Video card, HD or any other PCI adapter. It's GOT to be the mobo or CPU right?

Wht I'm wondering is, which is it more likely to be? I don't have a spare of either lying around, so either way I've got a 50/50 chance of buying something I don't need.

Is there any additional tests that anyone can think of that might rule out either the mobo or CPU?

The CPU is an Athalon XP, I think 1500 Mhz or something like that. The mobo is whatever came with the PC. I'm going to check Compaqs website to see if I can get a Manuf and model # for the mobo. I don't know much about AMD's.


Thanks in advance,


-Steve

 

My mistake, it's actually a K7, not an Athalon XP.


-Steve

 

I understand why you would think you've ruled out the components you
mentioned. But it's not necessarily so. I've seen computers that wouldn't
power up without the ram and hard drives connected.
Let me ask you... Do you get any beep codes going on?
You know, when you manage to get it to power up, do you get
any on-off beeping that is different than in the past?

 

Well, put it this way...with the HD and RAM removed, it acts exactly the same.

Besides, a PC will power up and stay on without an HD or RAM.


-Steve

 

I had a similar problem with my computer restarting for no reason.
My problem was the power supply going bad.
After five or six times of this happening (over the course of a few weeks) it finally died and burned up the connection to the mother board.
I was using a 300 watt power supply which was to small for my system.

 

Yeah, I was hoping thats all it was. Unfortunatly, when I hooked up the new power supply I got the same results.

I think I may have located a replacement motherboard. I just wish there was a way to isolate the problem from the mobo or the CPU.


-Steve