That was done with LN2, just cold water I could hit over 6GHz.
XTu's stress test is basically a form of Prime95 so yest it works. Some people think it's too hard on the CPU but... If you don't pass the test you're not going to score in the benchmark either.
I saw that earlier in your posts about stress testing. Stability is one thing that ,in benching is dependent on the bench. If you can finish the bench mark and get your SS it's stable enough.
What about the frequency one?