Beeps without memory is a good sign as it means the CPU is running but complaining about lack of RAM. The motherboard should at least POST even with faulty cache chips, as cache is enabled late in the process, just before booting.

What kind of memory modules are you using? FPM, EDO? Also, have you tried both PCI and ISA graphics cards?

There are exceptions to the rule. I just repaired a FIC 486-ELI-6 (VIA chipset) and as soon as a set of cache chips was inserted that had one defective chip, the board would do absolutely nothing. No POST screen, no video, nothing at all.
To make things worse it did start about every 100th time which made me suspect bad contacts or a temperature issue. I wasted several hours.
Disabling cache in the (AWARD-) BIOS didn´t change a thing.
So I had to drop the "cache is being initialized late in POST" theory.
The only valid test is "all cache chips out!".

TheMobRules wrote on 2022-11-26, 19:51:

What kind of memory modules are you using? FPM, EDO? Also, have you tried both PCI and ISA graphics cards?

Thanks for the reply. Well I think all of them are EDOs with couple of pairs. And no I'm not test with a ISA graphics card yet.

majestyk wrote on 2022-11-26, 19:57:

There are exceptions to the rule. I just repaired a FIC 486-ELI-6 (VIA chipset) and as soon as a set of cache chips was inserted […]
Show full quote

There are exceptions to the rule. I just repaired a FIC 486-ELI-6 (VIA chipset) and as soon as a set of cache chips was inserted that had one defective chip, the board would do absolutely nothing. No POST screen, no video, nothing at all.
To make things worse it did start about every 100th time which made me suspect bad contacts or a temperature issue. I wasted several hours.
Disabling cache in the (AWARD-) BIOS didn´t change a thing.
So I had to drop the "cache is being initialized late in POST" theory.
The only valid test is "all cache chips out!".

Okay, thanks. I'll remove all cache chips and try again.

Well I remove the cache chips, try an ISA graphics card and FPM RAM (2x8MiB Panasonic MN4118160SJ) but nothing changed. Any suggestion?

PS. The manual mentioned that it only support 4K refresh (The AB-PB4 support ED0 (Extended Data Output) DRAM and asymmetrical DRAM (4K Refresh DRAM)). Can different refresh cause this?

New 27 year old motherboard 😀 Maybe it was broken to begin with and thats why it spend its life in the box.

>80486DX4 100MHz
amd? intel? cyrix? there are at least 4 ways to jumper that on this board, go over jumpers with manual again, and list them here or take a picture

rasz_pl wrote on 2022-11-28, 03:45:

New 27 year old motherboard 😀 Maybe it was broken to begin with and thats why it spend its life in the box.

>80486DX4 100MHz
amd? intel? cyrix? there are at least 4 ways to jumper that on this board, go over jumpers with manual again, and list them here or take a picture

You are a very funny person. Both 80486 and i486 belong to the Intel, like Am486 for AMD and Cx486 for Cyrix.

It looks like AMD might not have known about 80486 "belonging" to intel 😀

so about those jumpers 😀

rasz_pl wrote on 2022-11-29, 10:01:

It looks like AMD might not have known about 80486 "belonging" to intel :) https://upload.wikimedia.org/wikipedia/commons/thumb/ […]
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It looks like AMD might not have known about 80486 "belonging" to intel 😀

so about those jumpers 😀

Yes Am486™ is a clone of Intel 486, Am I wrong?
Anyway the processor is a Intel 486DX4 and jumpers are in correct position.

dominusprog wrote on 2022-11-29, 15:35:

rasz_pl wrote on 2022-11-29, 10:01:

It looks like AMD might not have known about 80486 "belonging" to intel :) https://upload.wikimedia.org/wikipedia/commons/thumb/ […]
Show full quote

It looks like AMD might not have known about 80486 "belonging" to intel 😀

so about those jumpers 😀

Yes Am486™ is a clone of Intel 486, Am I wrong?

dominusprog wrote on 2022-11-29, 15:35:

80486 ... belong to the Intel

read fifth line of text from the bottom on amd cpu in the picture