I built a custom pc about a year ago and every so often when I went to turn it on it would flicker on and off once or twice before actually booting. When I woke up this morning I tried powering it on and it did that about ten times before I eventually shut it off. (Meaning all the lights/fans would come on for about a second before turning off.) My pc will actually boot every so often after about 5-10 cycles of it flickering on and off, and can load the OS and get to my desktop, but will quickly BSOD, the two I've seen are IRQL_NOT_LESS_OR_EQUAL and PAGE_FAULT_IN_NONPAGED_AREA. My pc did a system update last night and I'd like to blame it on that, but the flickering problem has always sort of been there. I'm not even sure where to start looking on this one.