I build my computer 2 months ago. i5 6600k GTX970 G1 Gaming 16GB DDR4 2400MHz Z170 - A 500GB SSD + 2TB HDD 750W (Corsair RM750) Windows 8.1 Everything was working fine but randomly (once a day, computer ~24h uptime) the computer screen freezes and there's a loud buzzing sound coming from speakers. It would only restart when I press and hold the power button - all the fans and lights inside the computer still working. This reapeats for some time and I have a hard time trying to pinpoint the problem. I formated my computer and installed windows 10 but it didn't solve the problem. So I changed to my old video card (Zotac GTX560 SE) and the problem is gone. What is the next step now that I found the problem? I don't know how to easily replicate the problem, I am only guessing that it is gone because I am using for some time the old video card and nothing happened. I am SURE that there's no overheating on the 970 (temps always stay between 40-50) and if the power supply can handle the old 560 it definetely can handle the 970. Is it maybe a defective card? Is so, there's anything I can do to test it? I once tried to run FurMark during 1h and nothing happened.