PM8400 mobo hung on boot

[Willy]

I bought a used Amptron PM8400. The BIOS ID on boot shows 2A5LAH09C. On POST, it has memory check and detected hard drive. After the energy logo disappeared, the board just hung. It did not attempt to boot from floppy. What could be the problem?

[DanU]

Can you post your other hardware? CPU, vidcard, HDD(s), CDROMs, memory, power supply, etc....

Maybe the HD has a bad boot block. Try booting from a floppy to see if that works.

[Willy]

I checked the hard disk with another board. It worked fine.

Last night, without making any changes to the board, I was able to boot up and ran Windows 98. I was able to power up and down for about three times. Then the problem came back.

On POST, it passed display test, memory test, keyboard test, and detected hard disk.

The problem aways occurs just after the BIOS detected the hard disks, check the CMOS configuration, and hung just before it looks for the boot disk.

I know the BIOS checked the CMOS configuration because every time I cleared the CMOS it gave me an message "CMOS checksum error. Default doaded".

Any suggestions will be appreciated.

[DanU]

Intermittent problems are always the toughest ones to nail. It could be almost ANYTHING. Flaky mobo, flaky ram, flaky HD, flaky PS, etc. At this point I would just try swapping parts out one at a time using known good components until the problem disappers.

My first guess would be a bad board. Amptron (a.k.a. PC CHIPS) motherboards have a reputation for poor quality. OTOH, my PM8800 worked flawlessly for over 4 years before being retired. It's currently collecting dust in the closet but I'm sure it still works just fine.

My second guess is a bad PS. A flaky power supply can cause all sorts of havoc, from intermittent BSODs to system-destorying power surges.

Good luck. Let me know how things work out.

[DanU]

Glad to hear you got it working. I typically notice a performance loss of 10% or more with the L2 (external) cache disabled, but at least it's working.

Write-back cache concerns the L1 (internal) cache. It's a method of writing data to the L1. The other method is Write-through. Write-back faster than Write-through. Here's a simple explanation of the two: http://webopedia.internet.com/TERM/w/write_back_cache.html

[Willy]

Problem now solved. After I disabled external cache, this board boots every time. This board uses Write-back cache. Even with external cache disabled, the 2nd boot screen showed write-back cache enabled.

Can someone tell me what is write-back cache?