OverclockingTo find the maximum overclock of our card we used a combination of GPUTool and our benchmarking suite.
The overclocks listed here were achieved with the default fan and voltage settings as defined in the VGA BIOS. Please note that every single sample overclocks differently, that's why our results here can only serve as a guideline for what you can expect from your card.
The overclocks of our card are 890 MHz core (5% overclock) and 1275 MHz Memory (6% overclock). While they are not spectacular, they are decent and promising. Remember, we left the fan running at its default speed. Also we did not tweak any voltages, even though software adjustment is possible on these cards - there is just no software yet to do that.
Overclocking the memory on these cards is quite different from any other card so far. Normally you'd expect rendering errors or crashes, but not with these cards. Thanks to the new error correction algorithm in the memory controller, every memory error is just retransmitted until everything is fine. So once you exceed the "stable" clock frequency, memory errors will appear more often, get retransmitted, but the rendered output will still look perfectly fine. The only difference is that performance drops, the further you increase the clocks, the lower the performance gets. As a result a normal "artifact scanning" approach to memory overclocking on the HD 5800 Series will not work. You have to manually increase the clocks and observe the framerate until you find the point where performance drops.
Overclocked PerformanceUsing these clock frequencies we ran a quick test of Call of Duty 4 to evaluate the gains from overclocking.
The actual 3D performance gained from overclocking is 4.9%.
Temperatures look very good. Reaching 38°C in idle is amazing and another testament to the efficient design of these cards. Being below 80°C under load is also very nice, but as you read further up in the review, the fan is a bit noisy in that case, so my preferred result would be a quieter card and ~85°C load temperatures.