Reply 3160 of 29604, by Skyscraper
I got the QDI US491P3 VESA 486 motherboard to post again, the issue is that it only posts one time out of ~200 (not an exaggeration).
With the video card in any other slot than middle one out of 7 the board is totally dead, the diagnostic post card shows nothing except that there is power. The same thing happens if the diagnostic card is in any other slot than the last one. With the video card in the middle slot and the diagnostic card in the last slot the boards comes alive and starts producing post codes but the codes are somewhat strange. Two times in total the board has posted, one time right after I removed the battery a couple of days ago and again right now. Once the board posts it dosnt complain about anything except, CMOS checksum error which disappears after entering the BOIS, loading defaults and saving, just as one would expect with no battery connected. Soft resets works fine with the board posting every time.
I have tested the cache chips in another board, they work fine and the board finds 256KB cache so thats not the issue.
I have tested the keyboard controller in another board, it works fine.
I have cleaned the BIOS chip pins.
I have looked for shorts, there are none.
I have tried switching memory and VGA card.
I have tried two different known to be good AT PSUs.
Kafka called, he wants his motherboard back.
New PC: i9 12900K @5GHz all cores @1.2v. MSI PRO Z690-A. 32GB DDR4 3600 CL14. 3070Ti.
Old PC: Dual Xeon X5690@4.6GHz, EVGA SR-2, 48GB DDR3R@2000MHz, Intel X25-M. GTX 980ti.
Older PC: K6-3+ 400@600MHz, PC-Chips M577, 256MB SDRAM, AWE64, Voodoo Banshee.