GoldenTiger:

I don't think 1.175 or 1.200v would be a problem, those are some decent heatsinks. My stock SSC was 1.137 on the single slot cooler.

Unless you like the smell of roasted mosfet I would advice you install some sinks on them. They do get pretty hot and when you up the voltage they will get much hotter. The copper sinks on my mosfets get up to around 122F.

So, what kind of clocks are you getting???