Overclocking

Last but not least on our tour of the GeForce GTX 460 is a look at the overclocking abilities of the card. As we discussed earlier, NVIDIA is heavily promoting the overclockability of the card to the press, proclaiming that they are regularly able to get most cards up to 800MHz. We’re in a unique situation today to put that to the test, as along with our 2 reference cards, we have an additional 4 vendor cards from our GTX 460 roundup to tinker with. With 6 cards on hand we have a non-definitive but still very useful sample set to work with to verify just how overclockable these cards are, and what kind of a power penalty this entails.

For the purposes of this section we are focusing on the overclockability of the core, but not the memory. NVIDIA’s weaker GDDR5 memory controller coupled with the tendency for memory overclocking to reduce performance through the need to use error detection and retransmission makes memory overclocking much more difficult and often a bust entirely.

As not all of our cards are exactly alike, we’ll quickly run down the differences between the various cards

  • 1x NVIDIA GTX 460 768MB Reference
  • 1x NVIDIA GTX 460 1GB Reference
  • 2x EVGA GTX 460 768MB SuperClocked: Reference PCB and cooler, factory overclocked
  • 1x Zotac GTX 460 1GB: Reference-derived PCB, custom blower-style cooler
  • 1x Asus ENGTX460 768MB TOP: Custom PCB, custom cooler, factory overclocked, voltage tweak
     
  Stock Clock Max Overclock Stock Voltage Overclocked Voltage
GTX 460 768MB Reference 675MHz 840MHz 0.987v N/A
GTX 460 1GB Reference 675MHz 825MHz 1.025v N/A
EVGA GTX 460 768MB SuperClocked #1 763MHz 850MHz 1.000v N/A
EVGA GTX 460 768MB SuperClocked #2 763MHz 840MHz 0.975v N/A
Zotac GTX 460 1GB 675MHz 835MHz 1.000v N/A
Asus ENGTX460 768MB TOP 700MHz 930MHz 0.975v 1.062v
GTX 460 1GB SLI 675MHz 800MHz N/A N/A
EVGA GTX 460 768MB SuperClocked SLI 763MHz 840MHz N/A N/A

Among our 5 cards without voltage tweaking capabilities, all of the cards are closely clustered together in terms of the final stable overclock, with only a 25MHz difference between the top and bottom cards. The 1GB cards ended up with slightly lower overclocks than the 768MB cards, which is likely a product of the 1GB cards containing further enable ROPs and L2 cache than the 768MB cards. Meanwhile the best overclock on a card we got without a voltage tweak was one of our EVGA cards, which was able to go to 850MHz. On average we were able to attain a 24% overclock over the GTX 460 reference clock of 675MHz, and in the case of the EVGA cards a 10% overclock over their factory speed of 763MHz.

The lone standout in the group is the Asus card, which has voltage tweaking capabilities that allow us to increase the core voltage beyond the GPU’s VID. Asus’s SmartDoctor software allows for the card to be overvolted to 1.087v in 0.0125v increments, however in testing we found that anything over 1.062v would ultimately cause the card to fall back to 405MHz, which we believe to be the card’s VRM protection kicking in after the VRMs overheated. At 1.062v we were able to get the card to up 930MHz, a 33% overclock from the factory overclocked speed of 700MHz, and 38% faster than the GTX 460 reference clock of 675MHz.

Overall the impact of overclocking is heavily game dependent. Core overclocking favors games that are ROP/shader limited and has little effectiveness on games that are limited by the total available RAM or by memory bandwidth. For this reason out of our subset of games core overclocking was most effective on Battleforge and Bad Company 2, while only moderately effective on Crysis and STALKER. On Crysis and STALKER overclocking was at best only marginally more useful than having a 1GB card. And even with its greater core overclock, the Asus ENGTX260 is not immune to this effect once the 1GB cards are overclocked – it still falls behind an overclocked 1GB card ¾ of the time.

Currently the sweet spot would look to be a 1GB card with a lesser overclock. The additional RAM/L2/ROPs more than makes up for the higher overclocks the 768MB cards can attain in most situations.

For the cards without voltage tweaking capabilities, the power consumption penalty for overclocking is very minor due to the fact that power consumption increases with voltage much faster than it does with frequency. For the stock-clocked cards this is a 15W-25W penalty, while the factory overclocked cards are even lower (thanks to binning) at just 9W. Meanwhile as expected the Asus card with its voltage tweaking capabilities ends up witnessing a larger jump in power consumption in return for its greater overclock capabilities: 70W.

With only a minor increase in power consumption and the use of very efficient coolers, the GTX 460 only experiences a minor rise in temperature when overclocking without voltage modification. All of our cards with the exception of the Zotac under Furmark only rise in temperature by a few degrees, leaving temperatures well in the safe range for these cards. Even the Asus card with voltage modification stays fairly cool thanks to its more aggressive fan, rising by up to 10C under Furmark but still only becoming as warm as our stock-cooled cards in the first place.

Last but not least we have the noise factor. Thanks to the very low increase in power consumption these cards experience when overclocking, the coolers on these cards have to do very little to handle the extra heat. For the cards without voltage modding, the amount of noise generated increased by less than 1.5dB, and in the case of our EVGA cards didn’t increase at all. This results in our GTX 460 cards remaining as some of the quietest mid and high-end cards we’ve ever benchmarked, even with a 24% overclock.

The Asus card is of course the exception to the rule here, once again due to a combination of the more aggressive cooler and voltage modification. Here the amount of noise generated shoots up by 4.4dB when overclocked, which is a fair trade for the overclock but is definitely going to be more noticeable than the rest of the cards in our collection.

With all of this taken in to consideration, there’s little we can do to argue with NVIDIA’s claims about the GTX 460’s overclocking capabilities. One thing we need to make clear before going any further though is this: overclocking is not guaranteed. In our briefings with NVIDIA, they have told us that they know not every GTX 460 can hit 800MHz+, which in turn is part of the reason why the stock clock is only 675MHz. We believe a majority of cards will be strong overclockers, but this cannot be applied to all cards. Buying a GTX 460 is still going to rely on the luck of the draw, only the odds are very good at the moment. So if you absolutely must have an overclocked card, then a factory overclocked card is still the way to go.

At this point if you do receive a strong card it makes little sense not to overclock thanks to the very small increase in power consumption (and as a result, temperatures and noise) that overclocking causes. This is as close to as free of an overclock as there can be for a video card, so run with it and enjoy performance approaching a Radeon HD 5850.

Finally, if you are going to overclock, what kind of a card should you be shooting for? As it turns out the reference cooler does a very good job of hitting a balance between cooling needs and noise, while Zotec’s cooler does worse and Asus’s cooler does better at a cost of additional noise. We will add that we believe that overclocked 1GB cards are a better way to go just like we believe that 1GB cards are the way to go when at stock clocks, but ultimately this becomes a matter of affordability. 

Power, Temperature, & Noise Conclusion
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  • Alroys - Monday, July 12, 2010 - link

    Nice review, but i would have liked to see how well they overclock. Reply
  • beginner99 - Monday, July 12, 2010 - link

    Not a bad card. I ordered a 5850 for my new build. 460 is a little less performing but more quite. The ordered 5850 is out of stock and no due date. However till the 460's arrive it will probably also be a few weeks...Need to wait on price. usually quite a bit higher here. Reply
  • KITH - Monday, July 12, 2010 - link

    Quiet and Quite are different words...

    460 is a little less performing but more *quiet*

    Usually *quite* a bit higher here.

    See the difference? You even used both in your own post.
    Reply
  • chizow - Monday, July 12, 2010 - link

    Looks like a great part from Nvidia that seems to hit the same target price and performance markets as the wildly 8800GT before it. Much as the G92 and its derivatives dominated the gaming market while bringing DX10 to the mainstream, GTX 460 may be poised to do the same. Reply
  • Griswold - Monday, July 12, 2010 - link

    Its not going to dominate anything but nvidias own lineup. AMD will just - finally - drop prices, and thats that. Reply
  • james.jwb - Monday, July 12, 2010 - link

    I agree. AMD will either drop the price on the 5850 to make this new card redundant, or not do it and make a major mistake. Reply
  • chizow - Monday, July 12, 2010 - link

    I doubt they're willing to drop the price on the 5850 enough to truly compete with the GTX 460, especially the 768MB version.. Maybe match the 1GB version's $230 price point by going to $250 but then what does that do to the 5870? Who's going to buy a 5870 at $400 when a 5850 only costs $250? Either way it looks like Nvidia has that $200-$250 market locked tight and in a few months with MIRs that'll shift to the $160-$220 range. Reply
  • Lonyo - Wednesday, July 14, 2010 - link

    Considering the launch prices were $260/$380, there's no reason to imagine a drop to $250 would leave the 5870 at $400.
    Maybe we would see something like $250/$350. Finally a drop from launch prices.
    Reply
  • papapapapapapapababy - Monday, July 12, 2010 - link

    i mean why bother? to play ports like "singularity" with bump mapped ( and terrible low res textures?) i mean the pos3 game only uses about 140MB of my video ram! ati, nvidia, intel, amd, no real pc games? > no sale. adeus suckers!

    Reply
  • mindbomb - Monday, July 12, 2010 - link

    What does the presence of hdmi v1.4 ports mean?
    Does this card have 3d bluray capabilities not seen on other cards?
    Reply

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