Hey guys, i recently bought a brand spanking new HD4870 for my gaming comp, and after fixing the fan speed at 37% and watching my temps drop to the 45-50 degree range i thought i'd see how much overclocking headroom my card had. I opened up the CCC and told it to "auto-tune" my card and it clocked my card at 840/1180. Needless to say I was thrilled since without any serious tweaking I was able to clock it that high. So anyway I ran 3Dmark06 to see how the card ran at those clocks and got artifacts all over the place. I looked at my temps and the card wasn't even hitting 80 degrees during the benchmark, so now i come to you, oh wise ones for advice. Is the CCC a bad tool to use for overclocking or am I just doing something wrong?

You can use CCC to overclock, just don't put any faith in the autotune feature. The problem is that the autotune feature does a very gross check for stability. It just doesn't scan long enough. To overclock with CCC autotune feature, you have to do it the old school way. Start by bumping up the clock speed for either mem or core, not both. After bumping it up play a game for a half an hour or run something like rthdribl to heat up your card. If you don't have any artifacting, then bump the same clock some more and test again. Once you find the maximum for that particular clock, back it down a bit and then follow the same procedure for the other. Personally I start by adjusting the core clock, then move on to the mem clock.

If you prefer the more automated way, ATI Tools, and ATI Tray Tools both have an artifact scanner which automatically adjusts clocks and then heats the card up and scans for artifacts. I have used both with excellent results. The longer you leave it run the more accurate it is at finding the maximum for your clocks. That said it usually takes awhile for new cards to be supported by these apps. You can check to see if your 4870 is supported by either one. If not, not all is lost, you can still use that scanning feature, you'll just have to adjust the clocks yourself with CCC.

Hope that helps.