Re: Weird RAM issue or Ubuntu at fault ?
how is your thermal looking, and does the shutdown seem to coincide with the usage of any particular device?
I had a guy last week with a dying nic. every time he dialed up to dsl, it would work about 10 min before blackscreening (cause the nic pulled too much power).
personally I would suspect the ram or mobo, but I really can't recommend OCing. the performance boost is negligible, and is fraught with peril (and not fun peril like at the castle anthrax).
Things are rarely just crazy enough to work, but they're frequently just crazy enough to fail hilariously.