Problem solved! It turned out that both of my two COM brackets were of a different standard. Honestly I didn't even know that there were two different standards back then. This stuff was already becoming pretty outdated for the most part when I started to learn about computers in the early 2000's. Anyway I'm pretty sure that this is the case with mwdmeyer as well. I found an excellent image that made it very easy to rearrange the wires to the DB9 connector.

Now my serial mouse works fine and I'm pretty confident that the board is finally 100% sorted. I will run some more tests and perhaps some overclocking fun to see how stable it really is. Thanks a lot for the photos by the way. If I encounter any stability issues I might consider changing that resistor to the original spec but for now I think I'll let it be. For the big caps I went for 2200uF but as far as I know it shouldn't hurt. Might even be better for overclocking if anything. Again, if I get any issues I might try with the original spec components so it's good to know what they are.

Next I'll try to get some decent photos for UH19 and then I have to decide what to actually do with this board now that it appears to be fixed😉 I can't really find much information about this particular board anywhere but the little I can find suggests that it used to be quite well regarded (apart from the awful capacitors). Seems to be pretty good for overclocking too so that's gonna be interesting to try.

Big thanks to everyone who helped me to sort this out!

PuuFa wrote on 2021-04-25, 21:16:

My apologies for the delay. I've been a bit busy but I'm happy to report back with some pretty good results! Not yet 100% there […]
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My apologies for the delay. I've been a bit busy but I'm happy to report back with some pretty good results! Not yet 100% there but close.

2.jpg
Can't say how satisfying it was to see this when I plugged it in for the first time. It also passed all my stress tests and diagnostics without breaking a sweat but there were still a few issues to iron out.

After the initial success it just suddenly died on me. After disconnecting everything it came back to life just to be dead again the next morning. This I tracked down to a problem with the K6-2/450AHX CPU that came with the board. You can see in my first post that the voltage setting jumpers are set incorrectly. Of course I corrected them before plugging it in but who knows the previous owner might have been running it as it was... It didn't even match any documented settings but considering that the jumpers were kind of set for single VCC I suppose it's possible that the CPU got 3.3 volts or more. Ouch! No wonder it's not happy. I threw in some random K6-2/500 and the problem was gone. One fixed, few more to go.

Next annoying but not so critical issue was that Win98se would always freeze during shutdown. Not any drivers or updates would fix it but disabling ACPI in the BIOS did the trick. I installed Windows ME just to see how it would behave and discovered that ACPI works fine with it. I suppose this confirms that it's not a fault with the motherboard but just Windows 98 being it's quirky self, right? I faintly remember seeing this same behavior back in the day too with one or more systems... It's been a while.

Now, as far as I can tell there's only one issue left. The COM ports don't work. Both of them. That's quite inconvenient because I don't have a PS/2 bracket so no choice but to use a USB mouse. It only works in Windows tho so that's not exactly the ideal solution. Windows recognizes the COM ports but doesn't recognize anything connected to them so I assume there must be a broken trace or a cracked solder joint somewhere. This will need some more poking around but I'd appreciate any advice if there's something more that I should consider. I should add that there seems to be some level of connection happening when I hook up an old external serial port modem as an improvised test device. It briefly blinks some leds when I search for modems in Win98 but it just won't be recognized. Windows ME on the other hand gives a significantly more prominent reaction. Whenever I power on the modem ME will completely freeze and only unfreeze when I switch the modem off. If I boot ME with the modem connected and powered on it will freeze during the boot. So likely it's just one trace somewhere, right? Could I somehow identify which pin in the COM header is not doing it's job? That would narrow down my search quite a bit.

Greetings.
I am using a translator.
The latest official BIOS for this board is A11b. The BIOS version in your photo is A11.1 with Soltek and Redstorm Overclocking logos. I would like to get this BIOS.

Greetings.
I am using a translator.
The latest official BIOS for this board is A11b. The BIOS version in your photo is A11.1 with Soltek and Redstorm Overclocking logos. I would like to get this BIOS.

I already put away the motherboard because I had some weird performance issues with it but I will look into it again as soon as I have time. Then I will upload the bios somewhere. I will let you know.

PuuFa wrote on 2021-07-29, 15:32:

Greetings.
I am using a translator.
The latest official BIOS for this board is A11b. The BIOS version in your photo is A11.1 with Soltek and Redstorm Overclocking logos. I would like to get this BIOS.

I already put away the motherboard because I had some weird performance issues with it but I will look into it again as soon as I have time. Then I will upload the bios somewhere. I will let you know.

Yes, this board has performance problems, but this can be fixed by drivers (via 4in1 4.33 + agp from 4.16) and by changing the memory registers using the WPCREDIT + WPCRSET program.

K6-2 500 + ATI Rage 128:

Yes, this board has performance problems, but this can be fixed by drivers (via 4in1 4.33 + agp from 4.16) and by changing the memory registers using the WPCREDIT + WPCRSET program.

That's interesting, I will definitely try it. Thank you! I was using 4in1 version 4.26 because it had good performance on some other boards. I will get back after few days when I have the time to do this.

Here you go:

For some reason I can't find 4in1 version 4.16 anywhere so could you please upload it here or provide a download link?
Also could you specify what exactly should I change in WPCREDIT/WPCRSET?

all you need:

phantom_sannata user ViA drivers:
https://disk.yandex.ru/d/c5CRLzzIgZwwmA
(asking administrators to save drivers in the driver library)

programs, screenshots, explanations for the maximum performance of MY SL-54U5+K6-2 500+128mb (2x64) sd ram pc-100+agp rage
128+awe64+pci lan. win98se
https://drive.google.com/file/d/1l82WsavpYHVN … iew?usp=sharing

about this computer:
https://www.phantom.sannata.org/viewtopic.php … 20x200&start=44