Overclocking

As always, we looked at overclocking these already fast 8800s to see how much more we could get out of the GPU. Since none of these cards were clocked higher than reference speeds, and we covered performance of the reference 8800 GTX and 8800 GTS in the launch article, we will be focusing on overclocking, power, heat, and noise levels for this review.

We overclocked these cards by using NVIDIA's coolbits driver tweak allow us to raise the core and memory clock speeds in set increments until they reach the highest point possible while still running stable. By running stable, we mean that the cards run our benchmarks for extended periods of time without any graphical artifacts or crashes. Below is a table of the cards and the clock speeds we achieved when doing our own user overclocking on them.

Card Core Overclock Memory Overclock
ASUS GeForce EN8800 GTX 629MHz 1021MHz
BFG GeForce 8800 GTX 649MHz 973MHz
EVGA e-GeForce 8800 GTX w/ ACS3 659MHz 1013MHz
Leadtek Winfast GeForce 8800 GTX 627MHz 1033MHz
MSI GeForce NX8800 GTX 652MHz 1040MHz
Sparkle Calibre 8800 GTX 631MHz 914MHz
Sparkle GeForce 8800 GTX 629MHz 1011MHz
XFX GeForce 8800 GTS 654MHz 866MHz

Keep in mind that the factory speeds of these cards were all reference speeds; that is 575/900 for the 8800 GTX and 500/800 for the 8800 GTS. With that in mind we can see that several of these cards got fairly high overclocks, especially on the memory clock. Something we noticed when overclocking (that we will see illustrated in our overclocking performance graphs) is that like previous generations of NVIDIA cards, the core clock generally makes a more significant impact on the overall performance of the card.

Note that the current version of the driver only allows adjustment of the core and memory clocks, not the shader clock of G80. We aren't sure if the shader and core clocks are derived from the same source clock so that overclocking one actually changes the other, but we plan on looking at shader core overclocking as soon as there is software support for it. Currently there is a way to increase shader clock through a BIOS flash of the cards, but we chose to focus on overclocking that was possible without resorting to flashing your card's BIOS for this article.

The MSI GeForce 8800 GTX managed to achieve one of the highest overclocks, with the EVGA e-GeForce 8800 GTX beating it slightly on the core but not on the memory clock. The XFX 8800 GTS was able to achieve a core clock speed of higher than some of the 8800 GTXs, which is interesting, but because of its scaled down shader core it will not be able to outperform a GTX. Interestingly, the card we had higher hopes for didn't seem to overclock as well as we would have thought. The Sparkle Calibre 8800 GTX, with it's elaborate HSF design and peltier cooler, didn't get a very high memory clock at all, but did get a core boost of 56MHz on the core clock which will help performance a little.

As a final comment on overclocking, remember that your own results may vary. Given the brand-spanking-new nature of the GPU core, it could be that NVIDIA chose 575 MHz as the final core clock in order to get the most cores running at that speed. Since they aren't offering a range of GPU speeds (i.e. like CPU releases), cores either work or don't work at 575 MHz. Whether the overclocks we reached are due to variability in cores or come from actual BIOS/card differences (not that most of the cards are really different) is impossible to say without a much larger sampling of units from each manufacturer.

Leadtek, ASUS & XFX Overclocked Performance
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  • peternelson - Saturday, November 25, 2006 - link


    I'm hearing rumours of an even never "dual" type card called 8850gx2.

    Anandtech can you reveal any news on this?
  • at80eighty - Wednesday, November 22, 2006 - link

    Annual Computernerd Wanfest of 2006 just rolled into town (im a wanking nerd btw :-p)

    what i saw in the papers was an ad for an XFX 8800 GTX. but this article doesnt mention it's existence (or i missed it)

    or did you pick he GTS as it was a better deal than the GTX?
  • Modular - Saturday, November 18, 2006 - link

    I was just wondering why there are no charts showing the core temps when the cards were overclocked. I'd be interested to see how much more heat these things crank out @ faster speeds. I also heard that they no longet throttle the GPU core when in 2D mode. That seems silly to me as it probably is a huge reason for the high idle power draw as well as the high idle core temps...
  • dpante1s - Wednesday, November 22, 2006 - link

    Would be very interesting to see a roundup just for the 8800 GTS cards as I think that many users may only afford to buy this one but would like to know which one of those is the best for overclocking...
  • crystal clear - Tuesday, November 14, 2006 - link

    More GeForce G80 Series Revealed
    Published on November 13th, 2006

    http://www.ngohq.com/home.php?page=Articles&go...">http://www.ngohq.com/home.php?page=Articles&go...

    G80-200, G80-400, G80-600,G80-850, G80-875

  • AnnonymousCoward - Monday, November 13, 2006 - link

    I believe your overclocking results are horribly flawed and misleading. The max core clock varies with each semiconductor part, so you can't just take 8 cards from different companies and determine which company overclocks the best! They all got different G80 dies.

    Now, cooling could affect the overclock amount. But based on the cooling results, there's no correlation. Look at Sparkle's poor overclock versus its great cooling, as well as EVGA's and MSI's great overclocking versus heat. No correlation.

    At least Page 5 said "Whether the overclocks we reached are due to variability in cores or..." But Page 8 showed more misunderstanding with "The temperature levels of this card under load are even lower than the XFX 8800 GTS by over ten degrees. This is somewhat perplexing considering that our Sparkle Calibre 8800 GTX sample didn't overclock very well compared to the other 8800 GTXs."

    The conclusion should have been "8800GTX's overclock between 627-659MHz", and don't bold the one in the table from the company that happened to get the best die.
  • shamgar03 - Wednesday, November 15, 2006 - link

    I concur, unless the author can present more evidence?
  • cryptonomicon - Monday, November 13, 2006 - link

    They're valueable to me :(
    Would love if they every got included on vid card roundups like these...
  • shank15217 - Monday, November 13, 2006 - link

    the new nvidia cards are doing great but just take a look at the older 7 series and compare it to the ATI offering. ATI 1950XTX hands the geforce 7 series its butt. I have a strange feeling the R600 will give Nvidia a run for its money.
  • xsilver - Monday, November 13, 2006 - link

    i found it interesting that on one of your graphs that the overclocked GTS is able to noticibly beat the GTX
    would it be possible at a more sane 1600x1200 resolution?

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