I bought this PC two months ago and this happened like three times. It happened two times when I disconnected the PSU power and connected again. Now It happened again but I just turned on my PC like everytime. It makes 3 short beeps. I read it's something with the RAM. I noticed when this happens, RAM XMP Profile gets disabled. I use the XMP to set RAM at 29.33mhz. Ram is 2x4gb T-Force Team 3000mhz