My 670 TOP won't even reach it's max boost speed in Heaven unless I increase the power target. So my experience is that it's rather pointless trying to increase GPU or memory clock without first increasing the power target.
But that being said, one thing ASUS really messed up with this card is the stock fan profile. Your card will run alot cooler under load if you run a custom fan profile that runs the fan at the same % speed as your temp in C. I got my TOP down from 76C to 64C while looping Heaven just by doing this. And the fan noise is not too loud at 60-70% fan speed. And since the 670 reduces core clock when you reach 70C (and again at 80C) this lets me run max boost of 1267MHz constantly, instead of having it dip to 1254MHz every time my card reaches 70C.
Asus ROG G55VW:
CPU: i7 3630QM
GFX: Geforce GTX660M with 2GB ram
RAM: 2x8Gb 2133MHz Kingston HyperX Impact (surprisingly the G55VW uses the 2133 X.M.P. profile)
Storage: RAID0 with 2x 256Gb Crucial SSDs (both msata, one in a sata adapter)
OS: Windows 10 x64
