1. Make sure you change your surge protector at least once a year, it should be at least 850 joules. The higher the number the better.
2. Make sure the ground is good in the outlet you are using.
3 Make sure the motherboard does not have a screw or other metal items jammed beneath it. Also make sure it is correctly lined up with the mounting holes.
4. Make sure a pet is not urinating into back of computer. This may sound ridiculous but I once had problems with someone going through a lot of power supplies. The power supplies always had a peculiar smell, it smelled familiar though. I visited the person to check the ground and to make sure they bought a new surge protector.
I noticed that they had cats. When I ask to see their computer it was on the floor and I seen a cat coming from behind the computer. I figured out that the cat was spraying the computer and it was getting into the power supply. I had them set the computer up off the floor and they did not have any problems after that.
5. I had a problem with another person spraying air freshener. They kept going through power supplies and when I would take it out of the computer it would smell like perfume. I decided to take the computer to their house myself. I hooked it up and just when I powered it up the person started spraying air freshener and you could see the fan of the power supply sucking the air freshener in. I suggested that they not spray it when the computer was on and they haven’t had a problem since.
6. I had one more problem that took me a while to figure out. I had a computer that kept frying power supplies they were over heating. I didn’t think it could be dust because the person was a very good housekeeper. I eventually learned the person lived on a dirt road and they had the computer sitting in front of a window. They opened the window often so when the dust from the road got stirred up the computers power supply fan would suck the dirt in. The solution to that one was to have them get their computer cleaned out more often then usual.
7. One I almost forgot, I had computers that would work when I had them but would not turn on as soon as the person got them home. I went to see for myself and it turned out that their power cord was bad.