I have had 2x4GB of RAM for the past 4 years, and I just bought another 2x4 set a few months ago. I couldn't get them to work back then, and I still can't seem to make them work. I'm using Windows 10 64bit (Had the same issue on 7 as well), and an ASUS P8Z77V-LK motherboard. The RAM in question is PNY Optima. I ran memtest on both new sticks of ram and got no errors. It boots with 2 sticks, but when I add 3 or 4, I get no display. The BIOS is behind a few versions, so I can try to update that today, but yesterday EzFlash wasn't working (Black screen). Also, the old and new ram are the same model.