Hey, I was wondering if you ever solved this issue. I was looking at my stuff yesterday and noticed that my 6670 is only running at 667 Mhz Memory Clock, and according to http://xfxforce.com/en-us/Products/Graphics-Cards/AMD/AMD-Radeon-HD-6000-Series/AMD-Radeon-HD-6670/HD-667X-ZHF3.aspx
it should be 1.6 Ghz. I have contacted Xfx but haven't gotten a response yet.
Amd FX 4100 Quad Core 3.6 GHz
XFX HD 6670
8 Gigs DDR3
Generic 450 Watt PSU