667? You mean 1333.
Do you currently have one stick or two? Your 6670 will be sluggish in modern titles as it's not a high end card.
Its DDR3 1333, don't think they ever made DDR3 677. Well technically 1333 bus clock is 677 MHz and the memory clock is 166. Another story.
Need a better video card and maybe overclock your FX X6 alittle. You using a stock cooler or a aftermarket one?
I'm using a zalman aftermarket cooler I've got it up to 3.9ghz using overdrive w/o getting high temps.