I always run gfxCardStatus which allows me to select my nVidia card and disable my iris graphics processor. I have been running the fans on full and most components are running at 50 degrees which is pretty cool.
However the system is still freezing, I'm pretty sure this is a software issue. Any other ideas of what might cause it? a system crash every few hours is no way to work, specially when I have made the effort to invest in the latest software and hardware.