Bizare Computer Problem

[jljensen]

I hope I'm posting this in the right forum (I think its a mobo problem) but here it goes. My family has an old 1 ghz computer that has traded hands quite a few times. It has worked great until recently when I went to turn it on. I pushed the power button and the machine started turning on and off again in very rapid succession until I switched the power off in the back. We have tried turning it on and off about ten times and just recently it worked and said that the BIOS had put the computer into safe mode and dropped the CPU speed from 1ghz to 750mhz. What's the deal? Is it overheating or something? Of particular note, there is a small fan that isn't turning just below the CPU.

Does anybody have any clue about what's going on? Help is greatly appreciated, - Jeff

 

[Rugger]

Please give some more system specs. Tell us about any sequence of beeps when turning it on. How long does it take to reboot? At what stage does it reboot (before/ after/during POST, windows loading)?

If it's doing this almost as soon as it is being turned on then, it doesn't sound like a heat issue. The small fan may be the chipsets northbridge, but withou more details I don't know.

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[tweebel]

Its quite normal for the BIOS to drop the CPU speed upon failure.

Your normal CPU speed is 7.5 (multiplier)x 133 MHz (front side bus). Because The BIOS sequence failed it dropped the front side bus to 100 MHz making it run at 750 MHz.

Like Rugger said, the small fan should be the chipset fan, you can replace it with a large passive heatsink.
I would also suggest you try the system with another PSU.

 

[jljensen]

It may be normal for the BIOS to drop the CPU speed, but it shouldent do it every startup... I exit the BIOS at the new settings (making sure to save,) and next boot up it does it again.

Heres how it goes: I press the button to turn it on and about 5 seconds later things start to happen (before then nothing happens), it makes a *tha* sound with every time the lights turn on and off (the keuboard caps num and scroll lights flash, the green power light on the PC itself, and the hard-drive being accsesed light.) at first the on and off patern is somewhat fast, then it slows down and stops. bringing up the bios. Nothing is displayed on the screen prior to that time. In the BIOS wondow it has me in the section with the CPU speed and on the right where it gives a short description of what the selected item is there is a red warning (that is there explainign what happend) it says:

"during the last boot-up, your system hung for an improper CPU external speed setting. Your system is now working in safe mode (BUS: 100 MHz, DRAM: 100 MHz, PCI: 33 MHz). To optimize the system performance and reliability, make sure the cpu speed conforms to the specifications of your cpu"
I left it at the settings it set, and it keeps doing it every time the computer turns on. After the BIOS comes up with that warning I can exit the BIOS and boot regularly from there.

Is it ok to use the computer normaly after this? and more importantly, how do we fix it?

-Jeff's little brother

p.s. if needed I could film the whole process so you can see just what is happening

 

[tweebel]

I know that problem from a PC in which the CPU fan failed, could save the CPU just in time. Have you already replaced the chipset heatsink/fan?

 

[endyen]

This type of cycling is common, when capacitors are failing. Look at the capacitors around the chip. Are any of them leaking? Are they all flat on top?
If none are leaking, and all are flat on top, it's probably a capacitor in your psu.