Problem running PI on Ubuntu with dual boot Windows 10

[joelshort]

I've recently been experimenting with PI on Ubuntu in a dual boot configuration with Windows 10 (see specs below).  I have each OS installed on two separate SSDs.  The problem is that in Ubuntu I can run one benchmark but half way through the second benchmark the computer locks and I get a black screen.  My first thought was that something was overheating so I kept an eye on the temps and nothing was off.  And this doesn't happen in Windows.

When I created the Ubuntu partition I set it up with 30GB root, 80GB home and 30GB swap.  I thought that would be plenty.

Anyone have any idea what could be causing this? 

[joelshort]

I think I found the problem.  This is a new PC to me and the previous owner had overclocked the CPU and RAM (with a water cooler).  I reset all everything to stock speeds and have run several benchmarks without problems.  What I don't understand is why this only happens in Ubuntu and not in Windows since both are using the same hardware.