Just thought I'd share some benches I did with my 670 against my old 470 SLI setup.
http://www.overclock.net/t/1256780/...th-ocd-now-with-7970-ocd/150_50#post_17461971
My GB card has a stock boost of 1059, and a Kepler Boost of 130MHz, so max boost on load is 1189MHz. I'm able to OC my card to 1337/1750 at 1.162V (which is the highest the voltage ever goes) unless I force it to 1.175V using EVGA Voltage tool, in which case I can run 1367/1750 stable at 1.175V.
This 130MHz boost is absolutely reliable at all times as long as my GPU usage is over 50% ... otherwise core clock drops to save juice.
The GB cards seem to have a higher power target than other 670's by default, I suspect due to the 8-pin+6-pin config. I have never seen anything near 100% power usage (93% is about the highest it ever goes), so I just leave power target on 100%.
On stock fan curve I've never seen >66C so no custom fan profile is needed on this card. I've never throttled due to heat, and like I say never had to raise my power target. I just bang up the core offset to +148 and mem to +495 and I'm stable at 1337/1750 at all times, with great temps. No muss, no fuss.
LOVE this GB 670 card.