After having achieved a stable overclock at 905mhz at stock voltage with no power increase I have found that going past 910 starts the card producing artifacts in games (tested with skyrim and battlefield 3) such as black and blue boxes. Upon raising the power limitation to +20 as Afterburner allows and then upping to 910, the problem remains the same. This suggests the furthest this card can go is 905mhz. I kept the mem at stock (1250) for this oc but found that I could push it to 1355 with no problem however I didn't see any gains from it. When testing the card with furmark the temperature never rises above 61 degrees, which is no hotter than it gets on it's stock voltage of 800mhz.
This card is famous for being massively overclockable, people report stable ocs of 1ghz - 1.1ghz and I've even seen people take it beyond that - so why is it that mine will not do this?
Some people have said this could be the power supply, others have suggested it could be a faulty card however I have been using it at stock for about 6 months now with few problems.
I hope someone can help with this.
CPU - AMD 6350 3.9ghz - 4.2ghz (Self overclock)
GPU - MSI Twin Frozr III Radeon HD 7950
PSU - XIGMATEK Tauro 600W (80+ Bronze)