MSI R4670 512MB Review
 

Relative to other HD4670s, this MSI card was a good overclocker. In the end I was able to increase the RV730 core and memory clock by 100 and 150MHz respectively. The HD4670's clocks were adjusted using CCC. Temperatures were monitored using CCC as well. To reach my final overclock I started by increasing the core and memory speeds by 25MHz until I hit system instability on anything above 849MHz on the core. I was able to increase the memory speed by another 50MHz from there however. In the end, any clock above 849/1149 caused instanteous and massive artifacting. Temperatures were never any issue in any of the testing as idle temps were in the low 30s.
http://www.overclockersclub.com/reviews/msi_r4670/