This is just a proof of concept/quick hack; I’ve recently been given a dead Cisco 3500XL. Plug the power cable in and I got no action, no fans, no lights, etc.. Removed the lid and looked inside: The power cables appear to be the same colors as a molex connector, so just like the Dell 2600 Series Sata Mod I decided there’s nothing to lose by giving it a go. As normal, the yellow cable is 12V+, blacks are ground, and red is 5V. Short the ATX PSU’s Pin 14 to 15 (PS_ON and COM), then watch the magic happen.
Yes it booted fine the first time, but after “cleaning up” the wiring, one of the cables must have come loose, hence the fault pic below. After properly checking the cables again, it booted fine and the console output is attached below. Would it be safe/recommended to use the switch setup like this in the long term? Probably not, but it’s good for testing and now I have a cable that can be plugged into any other 3500XL to test it it’s just a PSU fault or motherboard problem.