I still think you have a hardware problem. Ram is my suspect, but it`s possibly other hardware that`s faulty.
Unfortunately, it`s not always easy to diagnose which hardware is at fault.
Disconnect anything not required to run your system.
Leave just the psu/cpu/mobo/video card/1 stick of ram/hard drive.
If you still have problems, then the problem lays in what`s there.
If your system then becomes stable, then start adding one piece of hardware at a time and testing your system, until it crashes. The last thing you added will most likely be the culprit.
If your system is still unstable when running with the bear minum, then try the following.
Try another stick of ram.
Check your mobo for bulging or leaking capacitors. See
HERE for more info.
Check your hard drive, using the hard drive manufacturers diagnostic utility. If you can`t find it, see this thread
HERE.
Check that your psu is putting out enough power for you system. An underpowered or failing psu can cause all manner of system crashes.
Regards Howard