I have two FSP150-50PL Flex-ATX 150W switching power supplies that I received brand new with a strange problem. They have a 115/230 switch on the back, and being in the US, I moved it to 115V. I noticed the case was awfully warm for the low power motherboard and single hard drive it was powering. Then the power supply started shutting down, requiring that I momentarily disconnect AC power before it would work again. Sometimes the motherboard would lock up. In a nutshell, instability.
I tried the other power supply, which I did not initially notice was still set at 230V. It ran much cooler, and after hours of testing, no shutdowns or lockups.
I haven't tried the other power supply set at 230V yet, but I'm guessing it'll act the same. Isn't this really strange?