Thanks for the advice amuffin. Lots of people seem to be saying that 2500K/2600K is a conservative (mature?) option with colder running at overclock, and there seem to be some dogs of 3770K's out there that run super hot, or don't overclock well. Thats the problem with new chips I guess.
Its probably not an issue for people that switch their machines off when they are not gaming, but mine runs 4X100% 24/7 for extended periods. The software I use loads the CPU's at peak continuously (several billion integral calculations per day). I will off-load what I can onto a GPU, but not all software/models run on GPU.
I am not too impressed with some of the temps being quoted when running prime - (4.6GHz @ 1.23v. 86C max after 12 hours of prime; max overclock on $300 cooling,
4.7GHz @ 1.29v. 94C max after 2 hours of prime with RX360 radiator with 3 fans in pull config. XSPC Raystorm CPU Block, MCP655 pump on 4 out 5 speed setting).
Some air cooling e.g. cooler master hyper 212+ temps (80's C) at conservative overclock are not too great either. V6-GT is a little better (70's). Can't be good for the life of the CPU?
I think I will try air cooling with a high expectation of switching to liquid cooling solution if it gets too hot, and attention to case airflow etc.