There's three versions of it listed in TH99, none of those match your board?

No, the model number on mine is 8433/40 UUC instead of UUD.
I keep running into that, ... I had hoped that the numbers would still reference the same jumpers but no luck there.
I'll have to post pics as soon as I get back.

No, the model number on mine is 8433/40 UUC instead of UUD.

But the UUC version listed on TH99 isn't the same as yours either? That makes things a bit more complicated, if there's two different boards with identical model numbers...

Theres always the chance one of the 2 boards are made for an OEM...

Thanks guys. It turns out that my explorer was a little screwed up and kept displaying the same page no matter what link I clicked on 😖 .
I reloaded the page and now I have the correct link 😁 , I was kinda confused as to why so many boards had the same layout for a few minutes though 🤣 .
Anyway, there were a couple things that caught my eye earlier and I figured I'd mention them incase they're a major concern (I'm pretty concerned already about a few of 'em). First, there isn't any IC where the "KBD" is supposed to be. Second bank 0 cache chips are 28 pin (just like bank 1) but the slots are for 32 pin chips. Third the jumpers don't seem to match any configurations that I've read so far, so if it was powered up with incorrect jumper settings, couldn't that damage the board?

First, there isn't any IC where the "KBD" is supposed to be.

Is it an empty socket, or completely unpopulated? It's possible your board has an alternate configuration and uses a different chip (maybe one of the 'super IO' chips or something) for keyboard control, though if you have an empty socket it's also quite possible that somebody stole the keyboard controller off of it. The latter could be a problem, however not an insurmountable one. Usually the keyboard controller chips are relatively cross-compatible... i.e., since you have an Award BIOS and no PS/2, a keyboard controller from most any other Award BIOS-based 486 board (and probably also earlier Pentium boards) without PS/2 should work as a replacement.

Second bank 0 cache chips are 28 pin (just like bank 1) but the slots are for 32 pin chips.

That's fine, and is quite common. 28-pin chips can be used in 32-pin sockets, leaving the first two pin rows of the socket open. It was done that way to allow upgrading to higher-capacity SRAM chips... that board appears to allow 256K cache using either 8 32Kx8 chips (which is probably what you have) or 4 64Kx8 chips, and the 64Kx8 chips use 32-pin sockets.

Third the jumpers don't seem to match any configurations that I've read so far, so if it was powered up with incorrect jumper settings, couldn't that damage the board?

Really the only jumper settings that might cause damage are those for the CPU voltage. And even then, it would probably only affect the CPU, not the board itself. Also, don't assume that the settings listed on TH99 are a complete list... sometimes there's a bit of missing information, sometimes there are additional undocumented/alternate settings, and once in awhile, TH99 can be completely wrong.

A photo of the motherboard might be helpful.

I've been trying to upload some pics, but I might have to reinstall my OS on my main computer because javascript isn't working 😵 (java is required to use the site that I upload with). I'll post 'em as soon as I can 😀 .
Meantime, I decided to try booting up,... and the same problem happened that I had back with my soyo 4saw2. The system wouldn't display with any of the video cards I used (almost all were PCI although I tried a crappy ET4000 ISA and got the same results) without any beeps. I removed the ram to see if it would beep, and it did, but no beeps whether the video card was in the slot or not present at all.
The connected hard drive whirs up and makes that quiet clicking sound like it's seeking, and the keyboard lights flash but then don't respond after that.

You mean, it powered up but you got no display and not a single beep?
Have you tried another PSU?
And if it's the PSU (meaning the one you were using is defective), make sure you don't use it again as it might damage some of your precious motherboards 🙁

By nemesisv at 2011-05-21
Sorry, I haven't been able to afford a decent camera yet. But at least I finally got my internet browser to work again.
EDIT: I already swapped out the 28 pin sram for 32 pin sram because the timings were different.

How's this for an idea... bad bios chips? I ran some tests on 4 of my 486 boards (all pci) and found that only one board (soyo 4saw2) would display to the screen with only one of the bios chips I have (and even that one told me it needed a flash but refused to read the floppy drive). Tried several PSUs too and all seem to work perfectly with my ss7 units.

Just remember that carpets kill 😉

Tetrium wrote:

Just remember that carpets kill 😉

Yeah. I make sure to use the cardboard box for insulation and keep myself grounded whenever working with the hardware. Btw I set it up on my bed because I didn't have any other location to set up for the picture at the moment.

I ran some tests on 4 of my 486 boards (all pci) and found that only one board (soyo 4saw2) would display to the screen with only one of the bios chips I have (and even that one told me it needed a flash but refused to read the floppy drive).

486 BIOSes aren't interchangeable, they're custom coded for the specific chipset and board design. Of course a board isn't going to boot if you stick some random BIOS chip in it. Hopefully you kept track of what chip goes to what board.

And while it's possible for a BIOS chip to get corrupted, it's pretty uncommon. Being that you seem to be having the same sorts of problems with all your 486 boards, the most likely explanation would be that it's user error, not failed hardware.

It looks like at least part of the issue with that Biostar board, is that you have non-parity memory in it. That could even be the entire problem.

One thing I notice different is that the BIOS and RTC are in different locations from the Biostar boards that I have. The jumpers that reside near them are probably relocated as well since the space between the PCI and ISA slots is narrower. I also don't see a PS/2 mouse port. Is this an earlier revision of the 8433UUD?

Is this an earlier revision of the 8433UUD

Being that it's an 8433UUC, it would be reasonable to assume it is an earlier revision... what with 'C' coming before 'D' and such. 😉

Old Thrashbarg wrote:

486 BIOSes aren't interchangeable, they're custom coded for the specific chipset and board design. Of course a board isn't going […]
Show full quote

I ran some tests on 4 of my 486 boards (all pci) and found that only one board (soyo 4saw2) would display to the screen with only one of the bios chips I have (and even that one told me it needed a flash but refused to read the floppy drive).

486 BIOSes aren't interchangeable, they're custom coded for the specific chipset and board design. Of course a board isn't going to boot if you stick some random BIOS chip in it. Hopefully you kept track of what chip goes to what board.

And while it's possible for a BIOS chip to get corrupted, it's pretty uncommon. Being that you seem to be having the same sorts of problems with all your 486 boards, the most likely explanation would be that it's user error, not failed hardware.

It looks like at least part of the issue with that Biostar board, is that you have non-parity memory in it. That could even be the entire problem.

I made sure to check the chips so I didn't lose track of them although the one that partially works was never in the 4saw2 prior to me putting it there. Which surprised me when it actually worked (kinda). I have nothing to lose with most of these boards so I'm willing to try almost anything at this point. I didn't even notice the memory stats, so it's a good thing you pointed that out. It's very likely that it's user error, I just wish I knew what I was doing wrong 🙁 .
I'll post more when I find out.

Ok, I swapped the ram sticks out for parity and got no further than before. I then swapped the PSU out to a different unit and (though it worked before) the fan seized and some smoke curled up from the mess. I'm sure it's still fine though, PSUs do that all the time, right? 😢 (Ok, I know better than that.)
So after I buried that PSU beside the broken 4saw2 motherboard (oh yeah, I don't think I mentioned that. That's where I got my extra BIOS chip from.) Installed a new PSU and I'm back to square one.
I've been looking this problem up a lot and in my research this seems to be one of the biggest unresolved issues discussed online. Which means that I probably really screwed up somewhere with my initial setup on the 4 486 boards that I have tried recently. 😢
Oh, well. At least I'll know what NOT to do if I ever figure out how I screwed these precious motherboards. 😁

Those 486 boards are pretty easy to mess up as they have a lot of confusing jumper settings. It's easy to make a mistake and documentation of these boards is either hard to find, incomplete or just plain incorrect.
I always think 5 times before applying power to one, wouldn't want another one to go firecracker on me! 😜

RG100 had a mishap very recently also with a 486 board. He put a CPU in with the wrong orientation, got smoke and a couple scortch marks on the underside of the board and later found out both board and CPU still work fine!
Those things are hard to kill, but easy to make mistakes with 😜