Nvidia's GTX 590 is not a card that needs to be overclocked for gaming performance. Two GF110 GPUs, as found on the GTX 580, working in unison will kick any game's behind, and the idea of being short of frames with the card's stock clock settings is wild and preposterous.
What's intriguing about the spec sheet of the 590 though is that each GPU has been down-clocked significantly to sit safely on the same bit of circuit board (any lisping readers are invited to read that last part aloud).
While a big performance increase is evident from single to dual-GPU cards, the 590 doesn't produce twice the performance of the 580. That means there's potentially some untapped power in the 590.
Obviously the clock settings have been tamed for the sake of power and temperature. After all, there's only one fan lying between the two chips, and it'd be an awful shame to overheat the card and damage so much expensive circuitry.
Why risk it?
Well, firstly it's a lot safer to mess around with clock settings since Nvidia implemented a core voltage limit in their latest v267.91 driver release. The default 0.938V is now locked down.
Okay, that's slightly less headroom for overclocking, but voltage is unwise to mess with unless you're really sure what you're doing. There are already fables of people exploiting the previously unlocked voltage control and blowing up their 590s. Remember to update your drivers before you start tweaking, eh?
The biggest motivation for this overclock though, is simply to push graphics card performance to the limit. The GTX 590 is currently not only the fastest but also most expensive graphics card out there. Anyone who owns one does so to own the best of the best. So what if the best can get a bit better?
The best thing about overclocking your graphics card is that you can do it all in Windows - being able to push the numbers up and check stability without constantly restarting and going back into the BIOS saves a lot of time.
Using MSI Afterburner allows you to not only alter shader/core and memory clocks and fan speeds, but also monitor temperature too. The reference GPU core clock is 607MHz on a GTX 590, and 772MHz on the 580, and the processor clocks match up 1,215MHz to 1,544MHz.
There's also a 300MHz down-clocking of the memory clock as well. Those huge gaps makes it tempting to ramp up the clocks by large imcrements immediately (using the logic that it's the same GF110 chip) but it's quite simply impossible to match the 580's spec.
Don't see that as the final objective. Instead, bump up one individual core in 10MHz increments, leaving the cores you're not overclocking at stock levels.
That said, Afterburner allows the core and shader clock adjustments to be synced, which is recommended as manipulating these cores independently can lead to unnecessary instability rather than heat or voltage holding you back, these cores simply don't operate properly when one's hugely overclocked and the other isn't.
Slow and stable
Moving up in such minute amounts sounds slow and painful, but you'll soon see if your system's stable by running a benchmark like Unigine's Heaven. If it crashes, your system's not stable…
The reference fan attached to that GTX 590 is mild-mannered at low speeds, but at 100 per cent it's a hair dryer from hell. In order to get the biggest overclock, it will need to be running at full speed. We wait with baited breath for some aftermarket coolers with a fan for each GF110 chip, but until that day, it's just the noisy old reference fan chugging away.
Once you've found the tipping point for each core, it's time to overclock multiple cores. It really helps to run a benchmark that gives you minimum, maximum and average frames per second as this will show which cores are boosting performance the most, and as such which are worth trying together.
Again, don't expect miracles, log every benchmark result and crash.
Hitting the heights
Overclocking results will never translate directly from one machine to another, particularly with different PSUs: there are too many variables. However, we managed to get the core clock running at a stable 687MHz with no other cores overclocked, and again the individually overclocked memory core running at 1957MHz without any tantrums.
When both GPUs are overclocked together, core and memory clocks run stably at 657MHz and 1,857MHz respectively. And, give or take a few megahertz here and there, most systems with a decent PSU should be able to handle similar settings.
That's a respectable step-up in raw numbers and adds a few extra frames to the games it already blitzes. But then, it was never about improving gaming performance, was it?
The GTX 590 is a graphics card for reaching extremes, and those extremes are that little bit more satisfying for having reached them yourself.
The final stable core and memory clock settings offer yet more surplus frames to the most demanding graphical tasks out there.
It's worth noting factory overclocked versions of the GTX 590 will enter the market sporting clock settings that can be approximated, if not matched, by some simple software tweaking with the reference card.
DirectX 11 performance
Heaven 2.5: Frames per second: Higher is better
DirectX 11 gaming performance
Just Cause 2: Frames per second: Higher is better
AvP: Frames per second: Higher is better
Load temperature performance
Load: Degree Celsius: Lower is better
First published in PC Format Issue 253
Liked this? Then check out Overclocking guide: overclock your CPU, graphics card and RAM
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