GeForce GTX 460 1GB Overclocking

The more expensive GTX 460 1GB version is based on the full-fat GF104 GPU and so has the maximum 256-bit memory interface. This is because the 1GB version of the GTX 460 has more memory links, and therefore more memory bandwidth. While the GTX 460 768MB has only six links to memory, so has only six 128MB memory chips on the card (6 x 128MB = 768MB), the GTX 460 1GB GPU has the full eight connections (8 x 128MB = 1GB). As each memory connection is 32 bits wide, the GTX 460 768MB has a 192-bit memory interface (6 x 32 bits = 192 bits) while the GTX 460 1GB has a 256-bit bus.

Both of these memory factors result in much better performance – many games like to dump 1GB of data into a graphics card, and more memory bandwidth improves performance when dealing with high resolution textures and blend effects such as AA. However, having more active units within a GPU can hamper its overclockability – we wanted to see by how much (if at all) and whether the extra memory performance would outweigh any overclocking deficiency.

We found that overclocking the GTX 460 1GB was remarkably easy and yielded excellent results. We incrementally increased the core clock, and when that could go no higher we increased the memory speed. We were aiming for the same speeds as the GTX 460 768MB, but that was unfortunately unobtainable, as we expected. In the end, we managed to get the core clock from 675MHz to 845MHz, the stream processors from 1,350MHz to 1.690MHz; the GTX 460 768MB GPU hit a core frequency of 858MHz with its stream processors pushed to 1,716MHz.

We pushed the memory from 900MHz (3.6GHz effective) to 1,100MHz (4.4GHz effective), which is still a very respectable overclock. This is actually a slightly greater overclock than we managed with the GTX 460 768MB despite the 1GB card having two more memory chips that could potentially cause problems; the memory of the 768MB card could only overclock to 1,050MHz (4.38GHz)


The result of overclocking was just as impressive as with the GTX 460 768MB though. Even though our maximum GPU overclock was slightly lower than with the 768MB card, the extra memory bandwidth offered by the 256-bit bus and slightly higher memory frequency gave the 1GB card the edge. At 1,680 x 1,050 in Crysis we saw an almost playable 21fps minimum and a 34fps average – a noticeable jump from the stock-speed minimum of 16fps and average of 28fps. The overclock allowed the GTX 460 1GB to out-perform the £270 GTX 470 and almost keep pace with the £320 ATI Radeon HD 5870.


Again we were impressed to see that our large overclock and leap in performance wasn’t met by an offensively loud cooler or temperatures more at home in an AGA. The Zotac card that we tested maintained a GPU delta T of 49^oC and didn’t sound much louder than it did at stock speeds.

Conclusion

Both versions of the GeForce GTX 460 are worth considering, but of the two, the 1GB card is the version we’d buy. It’s only £20 more than the 768MB but performs much better thanks to its greater memory bandwidth and game-friendly 1GB of memory. When overclocked, the GTX 460 1GB is hard to pass over even if you’ve got an extra £100 to spend on your next graphics, let alone another £20.

Not only was overclocking the GTX 460 1GB easy, but it didn’t come with significant downsides – the card wasn’t much hotter nor much louder – and yet the performance rivalled that of much more expensive cards. We saw speeds that almost rivalled a £320 Radeon HD 5870 - amazing from a card that costs almost half as much. Even better, with many manufacturers releasing pre-overclocked 1GB cards with core frequencies of 800MHz or higher, we’re reasonable assured that our overclocking results are indicative of the GPU and not a freak. If you haven’t placed your order for a GTX 460 1GB already, do so while stocks last!