Overclocking is a pastime that carries no guarantees against breakage. For this reason, tinkering with a £1,000 graphics card is a little unsettling. Still, we can think of worse ways to spend a Friday afternoon, and initially overclocking looked promising. Using EVGA's excellent Precision overclocking tool
we could push the core frequency up from 648MHz to 782MHz.
We could push the stream processors way up the frequency scale too, from 1.476GHz to 1.8GHz, and we could wring 1.6GHz (3.2GHz) from the 1.242MHz 2GB of GDDR3 memory. This is a huge overclock for every part of the card - roughly a 21 per cent overclock on the GPU and a 45 per cent overclock on the memory.
at 2,560 x 1,600 with 4x AA as a stability test, we found that this overclock, while stable and showing no signs of corruption or artefacting, actually lowered the frame rate by around 10fps. Weirdly, and despite GPU-Z
agreeing that the overclock had been applied, 3DMark06 gave an identical score whether the Mars was overclocked or not.
Puzzled, we stepped down our massive overclock and tried Crysis
again, but still saw a drop in performance. Even a modest overclock saw no improvement in either 3DMark06 score or Crysis. It seems that the Mars has been made with neither interplanetary travel nor overclocking in mind.
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Not even absolute failure to overclock could dampen our spirits though. After all, we still had Quad SLI testing to do! Starting off with Fallout 3
once more, initially all seemed good. We saw good increases in frame rate when we didn't use AA, and we saw playable minimum frame rates when applied AA.
However, things got progressively worse as we worked up the resolution scale. At 2,560 x 1,600, with or without AA, the SLI setup was slower than a single Mars. We can likely put this down to a driver bug at this resolution, but even that seems silly given that Nvidia would surely want the Mars (or an SLI pairing of GTX 285 cards) to be the ideal choice for someone with a 30in screen.
Playing S.T.A.L.K.E.R: Clear Sky
turned from a joy to a tragedy with the installation of a second Mars. The decent performance of the single card was severly reduced when we added the second. While we previously had a playable minimum frame rate of 29fps at 2,560 x 1,600, the Quad SLI twin-Mars setup could only manage a meagre minimum of 14fps.
In all the other games the frame rates were barely effected by adding a second card. It's difficult to tell exactly why this might be so - it could be that our Core i7 965 CPU was holding the cards back, that games' engines don't allow higher frame rates than those achieved by a single card or that the second card was disabled for those games.
We tried re-installing Windows from scratch and only using Quad SLI to verify our findings (a trick that has worked in the past) but found the same performance. All of this means that while buying one Mars card is nigh-on impossible to justify, adding a second is pure lunacy unless you're only going to run Folding@Home