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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  • threedeadfish - Monday, July 12, 2010 - link

    I know you guys are all up in arms when a company releases information about up coming products, but you know that's information that can help a consumer.. I was looking for a card that was powerful enough while being quite and not using too much power. I ended up with a 5770 and I think it's a great product, however this the 460 offers 5830 performance at 5770 power and noise for only $30 more. I would have waited another week if I had any idea this was coming. You can't tell me nobody at Anandtech knew this was coming. Your anti-paper launch campain has a down site, it doesn't give consumers valuable information and as a result the video card I'll be using for the next couple years will be much less powerful then it would have been if the 465 artical just gave me a heads up, or just a little message saying hold off on $200 video card purchases something's coming. I only buy a new video card every few years please give me the information I need to make the best purchase. In this case waiting another week is what I should have done. Reply
  • notext - Monday, July 12, 2010 - link

    If you notice, everyone put out their info on this card today. That is because an NDA. Even suggesting anything about this card without nVidia's permission is a quick way to guarantee you won't get future releases. Reply
  • Phate-13 - Monday, July 12, 2010 - link

    Euhm, where can you find the "at 5770 power consumption"? The tables are quite clear that it uses 40-70Watts MORE under load then the 5770.

    And indeed, there is something called and NDA.
    Reply
  • Phate-13 - Monday, July 12, 2010 - link

    **** this. I want to be able to edit my posts.

    'something called AN NDA.'
    Reply
  • Death666Angel - Thursday, July 15, 2010 - link

    This is a review site, not a news or rumours site. If you are interested in the what the next couple of months bring from companies like Intel, AMD and nVidia, you need to start using sites like Fudzilla, that report hardware news and rumours.

    And trust me, there was plenty of information on the 460 being in the making and probably outperforming the 465 at a lower price point. :)

    And if you regret the purchase of a 9 month old card because one that just got released has higher performance (20%-40%?), while using more electricity (20%), costs more (60% - 130€ to 210€ for the cheapest cards each), you are going to be a very sad PC buyer, because normally, a new product will be faster _and_ cheaper, while now it is just faster, but a hellovalot more expensive too. :-)
    Reply
  • Lord 666 - Monday, July 12, 2010 - link

    Definitely some details missing for a complete picture on this card. Reply
  • Lonyo - Monday, July 12, 2010 - link

    There's more too.

    No real discussion of the reduction in polymorph engine to shader ratio, such as tessellation benchmarks (synthetic or otherwise).
    Nothing on minimum frame rates (and anything which is put up uses the older 10.3 drivers for ATI).
    In addition to the general compute performance benchmarks that you mention.

    Nothing about CUDA games (e.g. Just Cause 2) comparing the GTX465 to the GTX460.
    No consideration of ROP vs memory changes (i.e. is it memory bandwidth limited or is it purely the ROP reduction causing the performance hit on the 768MB card).

    Maybe the cards didn't come out in time. Maybe everything, or more stuff at least, will be covered in Pt 2, but it is somewhat disappointing that so many things are totally missing.
    Reply
  • Ryan Smith - Monday, July 12, 2010 - link

    You hit the nail on the head with your comment on time. I actually have the data, but with the limited amount of time I had I wasn't able to write the analysis (most of my time was spent on better covering the architecture). That will be amended to the article later today, but for now you can see the raw graphs.

    http://images.anandtech.com/graphs/gtx460_07111017...
    http://images.anandtech.com/graphs/gtx460_07111017...
    http://images.anandtech.com/graphs/gtx460_07111017...
    http://images.anandtech.com/graphs/gtx460_07111017...
    Reply
  • Lonyo - Monday, July 12, 2010 - link

    I hope I didn't come off as too harsh. I started writing and then towards the end realised it could be a time thing, and didn't go back to amend what I had written.
    After looking at most other sites, their reviews are sometimes even worse, covering only a very small handful of games.

    Thanks for the early graphs, much appreciated. Shame NV didn't give more time for proper reviews.
    Reply
  • jonny30 - Monday, July 12, 2010 - link

    - maybe in your country my dear friend.......maybe there i tell you ;)
    - in my country is 300 you see.......300 as a price start i mean :)
    - and for those 100 extra i buy another hdd for example, not another video card if you know what i mean
    - so, maybe is worth for you, but for me to jump from 4870 to this......
    - i am sorry, but it is not wort it........
    Reply

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