Diamond HD 4870 512 MB GDDR5

Overclocking

To find the maximum overclock of our card we used a combination of internal AMD OC Software and our benchmarking suite. At this time no public software supports overclocking the HD 4xxx Series, other than CCC which has a limit on how far you can OC.



The final overclocks of our card are 785 MHz core (5 % overclock) and 1150 MHz Memory (27.7% overclock). While the core overclock is lacking, the memory overclock is amazing and shows what potential lies in GDDR5. The great thing that for every 1 MHz you increase the real memory clock, the effective clock increases by 4 MHz. Please note that we tested overclocking the card with the default fan settings, if you increase the fan speed to 100% (loud!) you will definitely get more overclocking out of these cards.

I also noticed that memory clocking does not allow that much fine tuning with step sizes of around 25 MHz.

Temperatures

Those cards are running quite hot in both idle and under load. Please note that we used the hottest sensor of the die for our measurements.