Overclocking & Tweaking
Overclocking the R6870
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 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 will 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 - GPU 1.25V |
| Core Clock: 800 MHz | Core Clock: 850 MHz | Core Clock: 1008 MHz |
| Shader Clock: 800 MHz | Shader Clock: 850 MHz | Shader Clock: 1008 MHz |
| Memory Clock: 5000 MHz | Memory Clock: 5200 MHz | Memory Clock: 5800 MHz |
We leave the fan RPM control at default and reached a very decent overclock guaranteeing better results. Voltage tweaking is an option with AfterBurner (
Now there are a few things you need to know, in default Afterburner will not allow you to overclock over 900 MHz on the graphics core due to limitations set by AMD.
So 900 MHz is pretty much your limit. Should you be willing to take a little more risk then you can enable 'Unofficial Overclocking mode. Please follow my precise instructions here.
This will allow you to break away from limitations, at the cost of the possibility of running into stability issues as we are disabling AMD PowerPlay here.
So we now set the GPU at 1.25V and started to overclock. We reached 1008 MHz stable. The memory was stable at 5800 MHz (1450 MHz x Quad Datarate)
The temps did not change very much as the cooler keeps it under 70 Degrees C (click afterburner screenshot to the right), dBA levels remain roughly the same. You can also try and go a little higher by increasing fan RPM of course, your call to make. Here's what that brings you in added performance.
Above, we have Call of Duty: Modern Warfare 2, maxed out image quality settings as before with 4xAA 16xAF
Above, we have Battlefield Bad Company 2, maxed out image quality settings as before with 8xAA 16xAF
Above, we can see 3DMark 11 - the Performance mode is applied here. Oh and please do compare back and forth to a reference clocked R6870 as well, quite important as well.
