Overclocking & Tweaking the graphics card
Overclocking the R6850
As most of you know, with most videocards you can apply a simple series of tricks to boost the overall performance a little. You can do this at two levels, namely tweaking by enabling registry or BIOS hacks, or very simply to tamper with Image Quality. And then there is overclocking, which will give you the best possible results by far.
What do we need?
One of the best tools for overclocking NVIDIA and ATI videocards is our own Rivatuner. If you own an ATI or NVIDIA graphics card then the manufacturer actually has some very nice built in options for you that can be found in the display driver properties. Based on Rivatuner you can alternatively use MSI AfterBurner which will work with 90% of the graphics cards out there. We can really recommend it, download here.
Where should we go?
Overclocking: By increasing the frequency of the videocard's memory and GPU, we can make the videocard increase its calculation clock cycles per second. It sounds hard, but it really can be done in less than a few minutes. I always tend to recommend to novice users and beginners, to not increase the frequency any higher than 5% on the core and memory clock. Example: If your card runs at 600 MHz (which is pretty common these days) then I suggest that you don't increase the frequency any higher than 30 to 50 MHz.
More advanced users push the frequency often way higher. Usually when your 3D graphics start to show artifacts such as white dots ("snow"), you should back down 10-15 MHz and leave it at that. Usually when you are overclocking too hard, it'll start to show artifacts, empty polygons or it may even freeze. Carefully find that limit and then back down at least 20 MHz from the moment you notice an artifact. Look carefully and observe well. I really wouldn't know why you need to overclock today's tested card anyway, but we'll still show it.
All in all... do it at your own risk.
| Original | This sample | Overclocked |
| Core Clock: 775MHz | Core Clock: 775MHz | Core Clock: 973MHz |
| Shader Clock: 775MHz | Shader Clock:775MHz | Shader Clock: 973MHz |
| Memory Clock: 4000MHz | Memory Clock:4000MHz | Memory Clock: 4800 MHz |
Now we left the fan RPM control at default in all circumstances. We reached a very decent overclock guaranteeing better results. With AfterBurner (download here) our stable end result was roughly 975 MHz on the core and 4800 MHz on the memory.
We needed to bypass certain limitations though. The Radeon HD 6800 BIOSes are locked. This very 6850 will not go higher then 850 MHz. First up we need to bypass that, in the AfterBurner configuration file set EnableUnofficialOverclocking = 1
Restart AfterBurner, and now you can start overclocking. Increase GPU voltage towards 1.256 Volts which is enough, you need a healthy balance between heat and applied Voltage of course.
Now if your card allows it, it can take you really close to 1 GHz, we selected 973 MHz as it is stable. This resulted in temps of roughly 70 Degrees C and hearable yet considered normal noise levels from the cooler.
Here we have the card with Call of Duty: Modern Warfare 2, maxed out image quality settings as before with 4xAA 16xAF, keep in mind that the light blue bar represent baseline 6850 performance and the dark blue one the overclocked performance. It's roughly another 20% perf totally for free, matching the reference clocked R6870 actually.
3DMark Vantage - setup in Performance mode.
Battlefield BC2:, maxed out image quality settings as before with 8xAA 16xAF
