Yesterday, I bought a ASUS M5A78L-M/USB 3 Motherboard (and AMD FX 6300 Processor) and when I put it in my computer, and plugged it in, it turned on, without me pressing the on button, the CPU fan started, then turned off after 5 seconds, and didn't let me turn it back on with the power button. I went from a AMD Athlon II x3 if that's relevant. Any ideas why?