Overclocking the Palit HD4870 Sonic Dual Edition went slightly better than the last HD4870 I had reviewed. Booting up with the overclocked profile of 775MHz on the core and 1000MHz on the memory, I then proceeded to bump the clocks up in CCC until I hit the AMD limit of 790MHz on the core and 1100MHz on the memory. I felt the card still had a little bit of headroom left so I whipped out the AMD GPU Tool and pushed it slightly further.
With the stock cooler I was able to hit 800MHz on the core and 1150MHz on the memory. The memory overclock was quite substantial considering how stock clocks are 950MHz. I know the RV770 core on the HD4870 rather well and I know the core simply needs more voltage to scale higher. I suspect 850MHz could be done with ease on the beefy heatsink that Palit provided albeit with a voltage modification at the cost of voiding the warranty. The screenshot above was just displayed to show how GPU-Z incorrectly reads this card’s clocks, AMD GPU Tool and Catalyst Control Center work just fine.