Firstly P95=How to turn PC into space heater. Its does no real world testing. Just provides heat on a cold day.
Every chip is different you just have to find the sweet spot for yours. MOBOs can be a limiting factor as well.
What are you using for cooling?
The freezing after an hour could be memory, buffer over runs, insufficient setting of the virtual memory, HDD issues or MOBO components like the VRMs heating up. CPU and Ram issues normally present themselves within a few minutes.
I normally start with CPU first and clock it as high as I can get it stable, then cache, then ram, then video cards.
First sign of instability something needs toning down a bit.

“Two things are infinite: the universe and human stupidity, I'm not sure about the former” ~ Albert Einstein