Overclocking

As with the 7800 GTX, how the 7800 GT overclocks (beyond the factory clock) is something that we'll be looking at closely. Many of the 7800 GTXs had impressive factory overclocks, and the GT series looks to be no different. As we mentioned before, the XFX GeForce 7800 GT comes out of the box with a factory overclock of 450MHz core and 1.2GHz memory clocks. We were curious to know if we would be seeing the same core clock scaling that we saw with the GTX; specifically, if the performance increases were between the same frequencies.

Just to review, here is a brief explanation of what we saw happening with the 7800 GTX when adjusting clock speeds. Basically, we were seeing plateaus where consecutive core clock speeds had barely any impact on framerates (only a few tenths of a frame per second), then intermittent jumps up in performance between frequencies (i.e. between 472MHz and 473MHz). And because you get increasingly longer "plateaus" of minimal increase as you raise clock speeds, we've shown that this can cause for some confusion about how much faster each of the vendors' factory- overclocked 7800's really are.

After running some tests with Splinter Cell: Chaos Theory, we found that the frequencies didn't match up with what we saw with the 7800 GTX. We didn't see any jump in framerate between 472MHz/473MHz as we did with the GTX; instead, jumps occurred between 461MHz/462MHz and 477MHz/478MHz. We will be looking into this more closely in the next 7800 GT article, and hopefully, we can shed some more light on NVIDIA's frequency selection issues.

Interestingly, while attempting to overclock this card (the XFX GeForce 7800 GT), we managed to reach a core clock speed of 477MHz, which is actually a higher core speed than both the reference 7800 GTX (430MHz) and even some of the factory overclocked 7800 GTX's that we tested. This is equivalent to the performance that we would have seen at a 462MHz overclock. We did this without any special cooling systems, and the overclocking potential of these cards could be yet one more reason to choose the GT over the GTX right now. Buying a cheaper card and squeezing more performance out of it is maybe a better option than spending the extra money. But we have to say, as always, overclocking is risky and varies between cards, so if you plan on doing some overclocking yourself, we recommend paying very close attention to the warranty offered by the manufacturer.

The Card Performance Tests
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  • eetnoyer - Wednesday, August 31, 2005 - link

    There will be some changes, however, with fewer reviews that will cover more than one card.


    Followed immediately thereafter by another single card review. And with so many other 7800GT cards on the market already, they just couldn't find enough to do a round-up. Newegg currently has 13 listings in stock for 7800GT and Anandtech still can't manage to scrounge up enough. This site is starting to slide.
    Reply
  • bupkus - Wednesday, August 31, 2005 - link

    Are there any games out yet that require this kind of rendering power?

    I only play UT2004, but with my new X800 and a new Venice @ 2.3GHz I'm rockin' right now at 1280x1024.
    Reply
  • robere - Wednesday, August 31, 2005 - link

    I as well as 5 guys i know have a Dell 2405FPW that runs a native res of 1920x1200. I have a XFX 7800GTX ATH643700 SanDiego with 2G of RAM and currently run BF2 at 1920x1200 res with allmost everything on high and have a frame rate of 60-70. So when the next gen of games come out i am interested looking at SLI or next gen GPU. By the way BF2 at this res looks kick ass. Reply
  • JNo - Wednesday, August 31, 2005 - link

    I have a 2405 too and apparently widescreen is NOT possible for BF2 (check out widescreenforums.com) as the FOV hasn't changed. So even if you're 'forced it', you are getting the same width, it's just chopped off some of the top and bottom from the gaming world, and then zoomed in a little (giving you a little better visual impact but some gaming disadvantage). Let me know if you believe otherwise as a hell of a lot of people would like to know... Reply
  • Fluppeteer - Wednesday, August 31, 2005 - link

    Hi Robere,

    You may be able to answer a question... Can you tell me whether you have any
    problems if you run your 2405 from the single-link head of the 7800GTX? I gather
    the timings are quite tight to the single-link limits, and there have been
    reports of people struggling with the dodgy internal TMDS transmitters in
    the 6800 series. I'd like to know if nVidia have fixed this with G70.

    If the 2405 runs okay from that head (I'd expect it to work on the head with
    the dual-link head anyway, because the Silicon Image parts tend to be pretty
    clean) it presumably means nVidia have given their transmitter a redesign,
    which *might* mean the G70 could run my T221-DG5 properly (from both heads).
    It's kind of an expensive thing for me to find out without at least some
    indication that matters have improved. :-)

    (For people with less exotic - or at least, less discontinued - monitors,
    there are people considering Apple 30" display + Dell 2405 rigs, who would
    be equally interested in the answer.)

    Thanks!
    Reply
  • Rudee - Wednesday, August 31, 2005 - link

    I agree with the reviewer's final words that those looking for a higher end card need not look further than a 7800 GT, especially if you are playing in resolutions of 1600 x 1200 or less. Reply
  • Ozz1113 - Tuesday, August 30, 2005 - link

    Put it this way, I am upgrading from a 9500np modded to a 9700. I think you can wait a little longer from your 6800u ;]

    Too bad this review wasn't of the evga...not that it is all that much different
    Reply
  • Dmitheon - Wednesday, August 31, 2005 - link

    Agreed, I'm more interested in the eVGA than any of the others right due to that Battlefield2 bundle or the free mobo offer. Reply
  • robere - Wednesday, August 31, 2005 - link

    How about some SLI GTX/GT numbers? I have a XFX GTX and are intersted in what the GT can do in SLI. Reply
  • ukDave - Wednesday, August 31, 2005 - link

    Ditto, SLI numbers please. GT vs. GTX.

    From what i've seen the gap should narrow meaning even better money savings when choosing the cheaper GT option.

    I have two Leadtek 7800GT's atm and the reason above is why i chose them.
    Reply

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