I've just hooked up my new X800XT to the watercooling system and had a go at overclocking it. With the stock fan, I achieved 552MHz core which obtained a score of 6400 in 3dMark 05.
That's all fine, but when I overclocked the GPU with watercooling, I was able to push it to 606MHz core, before it crashed (still no artifacts beyond that, but I guess the voltage needs to be increased for a further improvement).
With stock cooling, the core temperature exceeded 80ºC at 552MHz
With water cooling, the core temperature never went above 50ºC at 606MHz
After running the benchmark again, it only scored 5,593 in 05 !?!
So 54MHz faster, yet almost 1000 marks lower?
The only thing I can think of is that it's creating errors within the core which is increasing the processing time needed?
Any thoughts?
(memory clock remained the same with both setups...562MHz)