Last Saturday morning, just as I was preparing to go to Mille Lacs, I discovered my MythTV server had stopped working. Luckily, just the power supply had burned out. I swapped the power supply with one from another less important computer and MythTV was up and running.
Tonight, I was curious why the power supply had quit. I hooked the supply to my test computer and it would not turn on. So I took the supply apart to see if there was a blown fuse or other part I could easily replace. The first bad sign was when I turned it over to unscrew the cover, I heard some small pieces rattling about inside. After removing the cover, I quickly located one of the problems. An IC had blown its top. If by some luck I could figure out what the chip was, it probably would not be worth replacing. The odds are other parts are blown.
The blown power supply was an Antec 300W supply. Using the Extreme PSU Calculator, I determined that I only needed 223W for my system. But after further digging, I discovered an option to derate the capacitors for age and continuous use. Factoring in capacitor derating, the calculator came up with a 290W. Also, I suspect the average PCI card usage of 5W is very conservative. I think my dual HD-3000's each draw at least twice as much power. They are always very warm to the touch. Doing the post par tum calculations, I think I did not have enough safety margin. I feel more confident that the 450W replacement power supply should be more than adequate