Curing a Dell motherboard's homesickness

2021-04-24

All I wanted to do was swap motherboards between cases, but one of the computers was a Dell, so naturally this process was more difficult than it needed to be. While some of the problems could be fixed with a file (no, not that one, the other one), the Dell motherboard refused to show any signs of life in the non-Dell case. I would hit the power button, and get absolutely nothing; at least the other motherboard had the decency to beep when it ran into an issue. The complete lack of any activity (no lights, no fans, no beep) suggested that it wasn't even hearing the power button being pressed, so I temporarily plugged in the front panel from the original Dell case, and it booted right up! How very odd.

For a long time, motherboard and case manufacturers couldn't decide on a standard for front panel connectors. Each component (button or light) would have leads terminating in a 2-pin female header, with a cluster of corresponding pins on the motherboard. Setup consisted of consulting the motherboard manual to determine which pair in the sea of pins was the correct one, and then struggling to seat the tiny header onto the pins. Because this is usually done once the motherboard is already inside the case, the pins are right next to the walls of the case, and the headers are tiny, one would inevitably miss and have to try again.

However, at some point, a 9-pin connector seems to have become standard. Or at least standard enough that both of the cases in question had keyed connectors, and both motherboards had matching pins: It's therefore not unreasonable to expect that these would be interoperable, but it's important to keep in mind that one of the computers was made by Dell.

Taking a look at the Dell connector, we see an unexpected feature: There's an extra wire connecting the power button ground pin to the reset button ground pin, without which the Dell motherboard refuses to turn on. One option would be to snip and solder the leads to transfer the jumper wire to the other case, but that would just leave the motherboard tied to the other case. Instead, we opt for a slightly more permanent solution: a piece of wire attached to the motherboard, which will sit underneath the front panel connector.

Serendipitously, I have a couple of spools of 30 AWG wire that is meant specifically for wire wrapping, even though I only learned about its intended usage now, while trying to describe it. No wonder it was so easy to roll up around a pin with a pair of tweezers! This is what the DIY jumper looks like on its own (for scale, the wire is 0.255 mm thick): And here's the final result: (Although the wire appears to be glowing, that's an artifact of my camera setup. I can assure you that this is not a high-current application.)

There's plenty of pin remaining above the wire to securely seat the connector: Despite the questionable appearance, this actually works!