I did some power supply swapping this weekend. My video editing PC had outgrown its 300-watt power supply and I needed something fast, so I bought an Antec 430-watt TruePower box locally. I paid $30 too much, and it’s definitely a show-off box, with gold plating everywhere and multicolored sheathing around the power cables. I don’t care at all about that, but I do care that now my jammed-to-the-gills video editing machine has lots of steady, reliable power. How jammed? It has one PCI slot and one drive bay open. It can suck down some juice.
I then turned my attention to my 1.1 GHz Athlon. I’ve been building it for months. At one point I thought the motherboard was bad because the system always hung after the second reboot during an OS install. Always. I tried different Linux flavors, different Windows flavors, everything. Then the problems continued after I changed the motherboard. Prior to that I’d suspected the memory, but that worked fine in other systems. Then I tried every hard drive I could lay hands on. It didn’t matter how great the drive worked anywhere else, if I tried to run anything but DOS on my AMD, the system wouldn’t let me finish installation.

Once I’d tried a different motherboard, that only left the power supply. My case is an Inwin, with a 250w Powerman power supply installed at the factory. I swapped in my 300W Antec–newly unemployed after being replaced in my video editing box–and the system became stable.

Rule number one, which I’d forgotten, is to always suspect the power supply when dealing with AMD stuff.

In all honesty, I don’t remember when I bought that Inwin case, so I have no idea whether that Powerman was AMD approved or not. But the Antec provides considerably more power on the +3.3v and +5v rails and it works. The Powerman powers old Intel (P2-class) and AMD K6 stuff just fine, but none of my Athlon stuff.

So if you’re cobbling together an Athlon from spare parts and it’s not working, either cannibalize or buy a decent-quality power supply, preferably one that you know has successfully powered AMD gear in the past. I’ll bet it starts working.