Are you running 2x8GB or 4x4GB sticks? It's not uncommon to have to reduce speed or increase latencies (timings) or increase voltage with 4 sticks of memory. I have 4 G.Skill DIMMs rated at 8-8-8 and would have odd issues booting every once in a while. Sometimes it would power on but black screen. Other times it would power on, get to my windows logon screen, and would hang there after entering my password for 20-30 seconds, and when it finally logged in, everything would run very buggy. Reduced timings to 9-9-9 and it's been smooth sailing since. Makes me wish I'd have went with 2x8GB sticks (not really sure why I didn't)