Adventures with a “working” Pentium III Motherboard

In my quest to build my perfect early 2000s gaming PC I decided to build it into a tower machine with a full width ATX motherboard so I had all the expansion I could wish for. I bought one from eBay that was “tested working” and found it was anything but…

I haven’t really blogged about this, but I was recently given a Pentium III 1GHz with 512MB of RAM in a slim Dell desktop case. I decided to upgrade it with things I would have liked to have back then to play everything I wanted. This included a Sound Blaster Live and a Voodoo II for Glide games. There was just one problem, the Voodoo II was too long for the case, so without a lot of metal work, this needed an upgrade. This is where the Ship of Theseus or “Triggers Broom” part of the story starts.

I removed the motherboard from the Dell as I saw it had what I thought was an ATX format. I checked the pinout of the PSU and it was ATX (unlike some Dells). The ports and card slots appeared to be in an ATX format, even though this had a daughter board, the slot for that could be used as a standard PCI slot. There is also the possibility to expand it to add more PCI slots as this motherboard was used in a tower case as well.

So I bought a cheap second-hand tower case and started to try to build the machine inside. This was the first problem. Although the motherboard was an ATX shape and used ATX power, it didn’t have holes in any of the ATX places. So I had no way to secure the motherboard to the case. The second problem was that it used proprietary undocumented connectors for buttons, lights and USB. Finally the one of the IDE ports was at an angle that meant it couldn’t be used.

I decided to get a new motherboard for this, one with lots of PCI slots, but also an AGP as my main graphics card is a GeForce. I bought an MSI MS-6309 motherboard which I later learned was a Packard Bell Saturn motherboard. It had everything I needed, the seller said it was “tested working”, I put in an offer which was accepted. And bingo! It arrived.

I built it into the case with a new PSU (as the Dell one didn’t fit), put all the PCI cards in, powered it on, and… black screen. No POST.

Problem #1

I then took a closed look at the motherboard (which I should have done before). To be fair, I didn’t spot this in the out-of-focus eBay photos either, but retrospectively I can see the really bad one in the listing.

Oh yea, those leaky caps definitely aren’t going to help. There are also a couple more problems in this image which I’ll get to later. I desoldered them to test them, sure enough they were so bad the ESR meter couldn’t give a capacitance reading.

They were replaced with some nice red Wurths. I tried powering on outside of the motherboard this time. Still dead. I removed and tested a few more capacitors that still looked good, these tested fine but I replaced them anyway.

Problem #2

I then noticed something off. A decoupling capacitor for the Northbridge had been snapped off.

I confirmed this with an image I found online of what the motherboard should look like. Which also helped me to determine the 10uF value. I soldered that on but still no joy. As it happens you can see problem #3 in the photo above too.

Problem #3

I eventually managed to get hold of a POST diagnostic card from Amazon. In true Amazon fashion the card’s output is entirely in Chinese, but Google Lens helped me translate it at least.

The translation said “Current diagnostic code: D4 Memory self-test, please check the memory or replace it”.

Well, I knew the RAM was good and 99% sure it should be compatible with this board. I also tried different slots, etc.

Then I took a closer look, something else appeared to be broken off, lets look under the microscope.

Somehow a 22ohm resistor between the Northbridge and RAM had broken off (how does this happen?!). Anyway, I happen to have lots of them in stock so replaced it. Try again…

Success! It was that resistor all along. I now need to finish building the machine. The only original parts remaining from the Dell will be the CPU and RAM. I’ve upgraded the Riva TNT2 it came with already and everything else is new (old) parts.