70c isn't bad - Ive have my rigs overclocked and had my cpu's in mid 80's and up to 91c (thermal shutdown)
Id take 70's in a heartbeat - nominal for an overclock
the keplers all stay in the high 50's and low 60's
since Ive gone complete custom WC loop(was air on gpu's before) all Ive got to say is the CPU affects my gpu temps more than my gpus affect my CPU temps
and nothing goes into 70's - mainly 60 or below - gpu's under 60c - cpu is higher
damn that pump even at low makes more noise than the fans at max(which are silent - do I hear birds chirpin - not thats the whine of the pump which changes speeds every once in awhile)...LOL
Yea do what is comfortable to you... we may be all fanatics so don't let us talk you into anything
if you need cooling check out CPU coolers even a WC LOOP(if you have room)