I have this cyberpower pc (I know, not custom built, but its too late to get the money back at this point). The components are displayed here
Mobo: gigabyte ga-b150m-gaming
GPU: Gigabyte rx 480 G1 4gb
CPU: i5 6402p
Ram: 8gb stick ballistix
PSU: Not branded
Game im using in this thread: SCP: Secret Laboratory
Essentially, the hardlocking occurs at anypoint in the computers usage, for instance, I could be watching a youtube video, and then the computer suddenly hardlocks, forcing me to restart the computer. I'm not sure if its just me, but I feel that the hardlocks increase in frequency after a hardlock just happened. Graphics settings also seem to help slow down the hardlocking problem by extending the 10 minutes before a hardlock happens on max graphics, to around a few hours on minimum graphics. Temperature also seems to do something in the computer since an AC cooled room seems to slow down the hardlocking problem further. Its not over heating since the pc's gpu is at an average of 65 degrees Celsius while the cpu is at an average of 38 Celsius at room temperature. I'm not sure what the problem is, but I can rule out ram being the issue. I don't have any other components to check with, so if I can't solve it with this thread, i'll likely hand over the pc to a reputable pc repair store.