Hi I have overclocked my x850pro to 537mhz/1250mhz 1.6ns, if I push the core or memory any higher atitool picks up artifacts and if i push the core up to 255mhz the VDU recovery resets the GPU clock using NGO ATI Optimized Driver v1.6.12.(Is there any way I can squeeze some more performance out of the core. I have a Zalman CF700 aluminum/copper cooler with idle temps of core 35/32 environment and load temps of core 55-65/ 39-40 environment (some x850pro owners have managed to push their core over 585mhz)thanks for the help.

AMD Sempron 3100 1.8GHZ @ 2.15GHz

ATi X850pro @ 545/1100mhz

NCP DDR400 1GB Ram @ 195MHZ 2.0/5/3/2/T1

Well you could try raising the voltage on the GPU it might help it might not. I don’t know what kind of M/B you are using but on my ASUS I can raise the GPU voltage under jumper free configuration its called AGP VDDQ voltage but if you are using PCI-e it would be called something else im not sure what they call it on PCI-E M/Bs. Or you could BIOS moded it and raise the voltage that way (I could never get them to work right.) Keep in mine that if you do raise the voltage that it will get hotter and it could kill the card. I have raised mine and its fine but that dose mean that it will work for you.
Heat is the enemy you could set some fans near it or beside it so that the fan on the GPU can such the cool air in. Or you could water cool it if you are already using water cooling that would help a lot because water transfers heat 30 times faster and holds over 4 times more heat than air. Or you could try using harsh language but it didn’t work for me LOL JK