I have had a Antec SmartBlue 350W power supply for about 3.5 years now. It always worked fine. Perhaps not the quietest. I have opened it up and replaced one of the fans with a quieter one and hooked up both to a fan controller. The problems started about 2 months ago. It's off and on. Basically, after extended periods of being unplugged (the switch in the back of the PS off), the computer will not power up. Sometimes it does power on but no POST, the fans just whirl at like half speed or something. This began to happen sporadically. The solution was just to leave it plugged in, switched on, and after maybe an hour, it would boot. Once booted, the computer runs fine through intensive gaming+video encoding what not. This morning, I shutdown the computer normally via OS command, and it refused to power up again. I tried a different power supply (no name 350w), system boots. I tried the Antec in another system, that other system boots. But the Antec will NOT power up my system anymore. Is this because the quality of the rails have degraded over time on my Antec and now the motherboard deems the voltages too far off from normal voltages? I have a Gigabyte GA-K8NS Ultra-939 motherboard. 2 hard drives, nVidia 6800GT and other ordinary components. Any suggestions would be great! Thanks for reading.