I have an HD 7850 1 OC 1 gb. Core clock stock is at 900 mhz and I can get it to 1050 mhz stable. Memory clock at stock is 1200 mhz and I can't overclock significantly higher to around 1300 mhz, whereas the max it can get is 1450 mhz through afterburner and even overdrive. The only similar case I have found was a review on Legit Reviews stating that their memory clock ran weird and had to keep on on stock when overclocked. Any reason to this?