I upgraded from a Crucial SSD C300 256GB to a Samsung 850 EVO 500GB. The computer is randomly locking up now. When it locks it is unresponsive,I have to hold power switch and force shutdown or it will eventually reboot on its own and boot to wrong hard drive. (or if i disconnect 2nd drive the evo will disappear in bios). The booting from wrong drive/disappearing problem only happens after windows crash. I don't think windows is the problem. I installed windows 10 twice and did a fresh windows 8 install. Same problem. This is on the computer in my sig. Here is the original thread about the upgrade http://hardforum.com/showthread.php?t=1871107&highlight= I am at the point where I think I might just try another brand ssd and use the evo in a new build that I am doing. I have been messing around with this for weeks.