Your computer will test the RAM for you if you tell it to. When booting press and hold whatever key kicks you into BIOS setup before attempting to load the OS. Sometimes F1, sometimes Delete, sometimes Insert, sometimes F12. If you can see your screen during a Safe Mode boot, then you can see the screen in BIOS setup. Look around for the option to either test memory or to run a full memory test at boot (usually set instead to Fast Boot or something like that since nobody wants to wait for a full memory check at boot).