Strange computer (PC) problem

I thought I was reasonably good at diagnosing PC problems, but this one’s baffling me. The system is an Athlon processor and has (or had) Win98/Linux dual boot. The symptoms are:
[li]When the PC is turned on, it starts to boot, usually gets past boot loader to the OS startup process, stops and reboots by itself, and repeats.[/li][li]It does boot up from a Win98 CD-ROM, but when I try to run scandisk on the hard drive it reboots by itself.[/li][li]I tried disconnecting the CD-ROM and moving the hard drive to the other IDE channel; same result (i.e. won’t boot from hard drive).[/li][li]Tried removing IDE hard drive and adding a SCSI card+drive (Adaptec 2940 plus external drive) - it doesn’t even boot up from CD-ROM.[/li][li]Problems started suddenly (i.e. not triggered by any configuration changes.)[/li][/ul]

I first suspected a thermal problem, but the CPU heat sink warms up so it must be properly attached to the CPU. The fan on the CPU heat sink is working properly.

So, any ideas? I already have a new IDE hard drive on order so I’ll try it when it arrives, but I can’t think of anything else to do short of replacing the whole motherboard.

One thing to try is remove every non-essential board and peripheral from the machine, and see if it boots. If so, you know the problem was one of the things you removed.

If the boot problem were only in Linux, I would point out that some Linux installations hang at boot time due to incompatibilities with APM (advanced power management) and Athlons.

The two most probable causes: power supply and mobo.

Probably your IDE controller or drive.

I too have had some issues with mine. Just because your heatsink is warming up means nada. In the past, my CPU would run between 90 and 100 degrees F when it was running perfectly normal. Now since the random booting, I’ve noticed that it runs at 150+ F! The processor is originally a 1GHZ Pentium III. Lately, it’s been getting really bad, instead of it booting every couple hours, it’s now booting every 5 minutes to every 30 secs. So, I clocked it down to 751mhz to keep it from booting until I get another chip.

Also, if it’s booting before it get’s to loading the OS, it’s probably not the OS. It’s either 1 of three things - Power supply, CPU or the motherboard.

My 2 cents, GL.

Try swapping out RAM sticks. I’ve found this sort of problem to be consistent with bad memory. The things you’ve described that cause this behavior, attempting to load the GUI after post and running ScanDisk, are both memory-intensive. When you boot from the CD-ROM, only DOS kernels and a minimal OS are loaded. the other suggestions made are also possible, but memory is the first thing I’d look at if I were working on this machine.

My system is also Athlon-based (1200+), and I began having similar problems a couple months ago – random lockups at first, then boot failures and shutdowns, or failures/shutdowns immediately after booting. (Running WinMe, no dual-boot.) I also tried swapping mobo’s, hard drives, RAM, video cards, power supplies, just about everything I could think of.

Since the heat sink/fan unit seemed to be functioning fine, I never thought about that, but that’s exactly what it turned out to be. Over time, the thermal transfer compound I had used when I built the system had deteriorated; it almost looked dried out, or cooked away. I removed and cleaned the bottom of the heat sink, cleaned (CAREFULLY!!) the top surface of the chip, shaved a tiny layer off the top of the chip’s rubber bumbers, applied new thermal compound, and carefully, but tightly, reseated the sink/fan. CPU temp dropped from 85 deg. C +/- to about 45 deg. C and the lockups/ boot failures completely stopped.

Thanks for the ideas! I’ve already removed all the non-essential cards, and tried swapping IDE channels, so I think those are OK. I’ll look at the thermal contact and memory first, and if those don’t work, I guess I’ll have to get a new motherboard and possibly power supply.

Why does this always happen at the end of the fiscal year right after we use up the budget? :frowning: (I know, Murphy’s Law…)

For heat, you can open the case & point a big room fan at the computer & if it works then, you need more fans. I usually need three fans or more. One on the power supply, one on the cpu & another in the front of the case. make sure the fans vents are clean, esp the power supply one.