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.