Hello! I have problem with my Radeon 7670 2gb 128 bit GPU (desktop not m version) . I overclocked it by AMD Overdrive to 900mhz on core. I've gone further and overclocked it by MSI Afterburner to 930 Mhz ( i ive added bigger fan to radiator and temperatures are going max to 64C). After 930 mhz graphic card became unstable - blue screens, shuttering etc. How can I get bigger Voltage on core. I unlocked voltage options in MSI Afterburner but nothing changed. The sliders are blocked. I really want to play Witcher 3 and im low on money right now. Maximum framerate in Witcher 3 is 25 after oc (without 13-18). So i think i can get 30 maybe 35 ?