Cold temps are fine but you don't want to get below 10*C because then it usually starts to build condensation if you have a normal ~ 22/25*C in the room,(watercooling). Other than that the cold won't have an effect on the processor. The temps you're showing are great. I would run the other games and check those temps before I messed with the current set up. If you want to see how well it does do then run OCCT HERE and see what the temps do. That program will run your processor at 100% for however long you want and show you the current temps of the processor cores and video card while doing it. What ever you get for a max temp during that you will probably never reach during your hardest gaming scenarios so you can be satisfied you have good cooling.
hi, dunno if i have done this correctly, anyhow, phenom ii's seem to be able to function at sub zero temps, not sure if its true, there was a mention of using liquid helium, -269c, i dont think this could be possible. the slightest stress on somethin this cold would shatter it.
But it does seem that AMD stuff as a much wider range (downwards) than intel stuff.