Overclocking the graphics card
Overclocking the GTX 580 DirectCU II
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 |
| Core Clock: 772MHz | Core Clock: 782MHz | Core Clock: 940MHz |
| Shader Clock: 1544MHz | Shader Clock:1564MHz | Shader Clock: 1880MHz |
| Memory Clock: 4000MHz | Memory Clock:4008MHz | Memory Clock: 4350MHz |
Overclocking wise the DirectCU II would allow to be clocked to roughly 850 MHz on the core without voltage tweaking. But if you [purchase a card like this, we doubt you'll not be tweaking the living bejezus out of it. So we applied a GPU voltage of 1.1v after which your overclock experience should go up a little.
We reached a stable 940 MHz on the core and put the fan RPM at 55%, which retains an acceptable noise level. Memory wise the we where a little thwarted and could not exceed 4350 MHz.
Anyway here's what that does towards overall game performance, I've included the reference card as well to understand and grasp overclock scaling in terms of performance increases a little better.
And our overclock applies to BOTH graphics cards setup in SLI. And while it is ridiculous to squeeze even more performance out of the two GTX 580 cards in LSI, it sure is fun to do.
Above, Crysis Warhead in DX10 "Enthusiast" mode with 2xAA, maxed out image quality settings as before. With so much GPU power requested by the game, we can actually measure the overclock pretty well.
Above, Battlefield Bad Company 2, maxed out image quality settings as before with 8xAA 16xAF. Here up-to 1920x1200 we run into massive CPU limitation. Once you are freed from that, perf boost upwards alright.
Above, 3DMark 11 - the Performance test and score. As you can see a nice additional bump in this very GPU limiting titles, lovely.
