I recently attempted to overclock my GTX 570 2.5 GB with limited success. I've been struggling to get the OC stable when bumping up the voltage. When I try and get the memory clock up around 2100 and the graphics clock around 900 the system starts crashing, and artifacts start appearing. Ive pushed the voltage up to 1.05 volts but that just seems to be making it more unstable, Temps are around 75c-85c when stress testing with furmark. This has lead me to think that something else is bottle-necking my system, here is my present build:
 
Graphics: EVGA 025-P3-1579-AR GeForce GTX 570 (Fermi) HD 2560MB
Mobo: EVGA E760 CLASSIFIED 1366 Intel X58 EATX Intel Motherboard
Processor: Intel Core i7-920 Bloomfield 2.66GHz LGA 1366 (Overclocked to 3.32ghz)
PSU: Rosewill BRONZE Series RBR1000-M 1000W Continuous@40°C
Ram: CORSAIR DOMINATOR 6GB (3 x 2GB) 240-Pin DDR3 1600
Overclocking Tools: EVGA PrecisionX
 
Does anyone see anything that could be slowing me down? I'm pretty new to GPU overclocking, so if anyone has any tips, that is also greatly appreciated.