Overclocking The GeForces
Although all of the cards featured in this round-up were already overclocked from the factory, we spent a little time overclocking them further to see what kind of headroom each had left. For these tests, we gave only the GPU a slight 100mV bump in voltage and increased the power target +20%. We then increased the GPU and memory clock offsets until we experienced instability or visual artifacts, or saw performance degradation.
Ultimately, anyone overclocking a GeForce GTX 600 series card has much tweaking to do. More often than not, you’ll find that increasing a particular voltage or frequency may appear to function properly, when in fact performance decreases due to errors or throttling. You’ll also find that the GPU Boost clock may travel above or below the offset value, when the power target is also increased.
The cards in our round-up all overclocked relatively well, achieving a minimum boost clock of 1240MHz and a maximum boost clock of 1369MHz. Please note, these frequencies were the actual peaks reported by the overclocking utility and not simply the sum of the offset value and stock boost clock. The Asus card, no doubt tanks to its huge cooler and custom power delivery circuitry (and a bit of luck) hit the highest GPU clock, while the ZOTAC cards had the most memory frequency headroom. The full breakdown on overclocked frequencies is laid out in the chart above.
While we had the cards overclocked, we re-ran the Metro 2033 benchmark at 2560x1600 to see what kind of performance increases were realized. All of the cards showed some improvement, but they were already fast to begin with.