it could be a few things. the first is that the ram is not running at the right speed. try cpu-z and look at the spd tab and see if your mb set the ram speed up right. also check that the ram you have now was on the mb qal list. you can try and run memtest on it. the second issue could be the gpu or cpu fan is over heating. running hardware monitor and watching your temps and voltage to see if one drops. (your mb bios may be old or a drive firmware may be old and when the pc trys to enter sleep mode it cant and hangs or reboots. for house cleaning i would run ccleaner..malwarebytes..make sure you only have one anti virus software loaded and it up to date and not expired. if it a few years old then uninstall it and install mse/avast/avg. run defrag and hdtune to check your hard drive.