256MB vs. 512MB - The Real World Performance Difference

More local GPU memory is never a bad thing, but it must be taken advantage of to be worth its high cost.  That means we need games with larger textures and higher detail levels to truly require 512MB cards, but given that the majority of gamers still have 64MB or less on their graphics cards - it's going to be a while before 512MB is necessary.  Game developers are notorious for developing "for the masses" and thus, will spend very little time on that which can only be taken advantage of by owners of $500+ graphics cards, today's 512MB card included. 

ATI's own marketing literature claims that the X800 XL 512MB offers up to a 40% performance increase over the 256MB X800 XL...at 1600 x 1200, with 6X anti-aliasing and 16X anisotropic filtering enabled.  The problem is that at such high resolutions with AA/AF cranked up, the X800 XL doesn't have the fill rate or the memory bandwidth to offer reasonable frame rates in most games, which is why we find the X800 XL 512MB to be more of a mismatch than anything else.  A faster GPU with more memory bandwidth would be able to offer more real world benefit when coupled with 512MB of memory than the X800 XL. 

That being said, let's look at the performance breakdown for the X800 XL 256MB vs. X800 XL 512MB at 1600 x 1200 with 4X AA and 8X AF enabled - pretty aggressive settings for the X800 XL to begin with.

As you can see, there is less than a 1% performance advantage to having 512MB with the X800 XL, even at these aggressive settings in four of the five benchmarks.  In Half Life 2, the 512MB card actually offers a fairly reasonable 11% increase in performance, but in the other games, the performance advantage is nothing.  The other thing to keep in mind is that 1600x1200 with 4X AA and 8X AF enabled is not the sweet spot for the X800 XL. In Chronicles of Riddick, for example, the performance offered at these settings just isn't smooth at all. 

The Half Life 2 performance boost is particularly interesting, but that was the only game we encountered where the performance boost was not only reasonable, but the game was also fairly smooth in actual game play.  However, at the price of the X800 XL 512MB, you are better off just purchasing an X850 XT and getting better performance across the board, including Half Life 2.

Although the single graph on this page pretty much tells the story of the X800 XL 512MB, we've included performance results from both X800 XL cards, the X850 XT as well as NVIDIA's GeForce 6800GT and 6800 Ultra on the coming pages, if you want to see things in perspective.  We included the X850 XT and 6800 Ultra in the comparisons because it is priced similarly to the X800 XL 512MB's suggested retail price.

The Test

AMD Athlon 64 Configuration

Athlon 64 4000+ Socket-939 CPU
2 x 512MB OCZ PC3200 EL Dual Channel DIMMs 2-2-2-10
ASUS nForce4 SLI Motherboard
ATI Catalyst 5.4 Drivers
NVIDIA 71.89 Drivers

Index Doom 3 Performance
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  • Fricardo - Wednesday, May 4, 2005 - link

    *terrible idea*
  • Fricardo - Wednesday, May 4, 2005 - link

    I knew that card was a terrible as soon as I read the title. How could ATI be so retarded? Doesn't even make sense...
  • Patman2099 - Wednesday, May 4, 2005 - link

    I could be mistaken, but isnt the Default FSAA on cards now using Multi sampling or mix of multi and super sampling?

    Perhaps ATI intends to bring back pure Super Sampling?
  • mbhame - Wednesday, May 4, 2005 - link

    Anand,
    There are more sites supporting your findings than contradicting your findings (ExtremeTech) - which wouldn't be a first for ExtremeTech.
    Your final comment in Post #21 couldn't have made me any happier - I'm tired of arguing with people who think slapping tons of RAM on anything dictates tons more performance, etc.
    Could you let us know how much is local and how much is shared system RAM in the recently-announced 512MB 6200's?
    Hey, when are you going to reply to my email? :P
  • Cygni - Wednesday, May 4, 2005 - link

    The card companies pushed 64meg cards when 32meg cards werent even close to maxed out. Then 128 when 64 was perfectly find. Then 256. Then 512. Its what they do, and the consumers have SHOWED the board makers again and again that they will pay out the nose for that extra RAM just to be "future proof", regardless of actual performance. They arent evil, but they have learned what sells. A 64meg card is JUST NOW becoming "needed" in most games.

    The two monitors i have in my house, Sony 200sx's (about 5 of em, all from around 1996 :D ) and early release 17in flatpanels (Dell and Mitsu) both are most useable at 1024x768, so i never even touch reso's higher than that in any games. Its not worth it to me. Personally, the gaganess for high reso, high AA, high AF gaming confuses me... especially at the increadible cost in both FPS and dollars to run that high. The visual difference is less noticeable than simple environ bump maps to me.
  • fishbits - Wednesday, May 4, 2005 - link

    Won't someone think of the poor starving gamers that don't have 256MB DDR3, much less an extra thus far-useless, overpriced 256MB of DDR3?

    Perhaps it could come in handy though in MOGs, where you're going back and forth through different zones and coming across the same characters multiple times, and it isn't as clearly defined as loading the next FPS level/map. "Hey, Jerx0r the Brave is still in video memory, don't have to reload him!" Of course it may not be a big hit if its already in system RAM, but with high-end systems running 1GB + 256MB, it's a decent bump up in total RAM.
  • AlexWade - Wednesday, May 4, 2005 - link

    Someone will buy it. Someone with deep pockets. If you are thinking about buying this card, can you give me some of your extra money?
  • Anand Lal Shimpi - Wednesday, May 4, 2005 - link

    ET

    I meant that it's not related to video memory size. If it were system memory related then it would affect both cards equally, but the test is cached and I noticed no disk related slowdowns during the benchmarking. If you really want I'll run it with 2GB of memory though, just ask and I shall do :)

    Take care,
    Anand
  • ET - Wednesday, May 4, 2005 - link

    Thanks for the comment, Anand. Why do you say "it's not related to memory size". Do you get the same scores with 2GB of RAM?
  • Anand Lal Shimpi - Wednesday, May 4, 2005 - link

    For those wondering, I also ran tests under Doom 3 at 1600x1200 with 4X AA (8X AF) on the High Quality setting. The performance between the two cards is as follows:

    512MB - 31.0 fps
    256MB - 31.0 fps

    This agrees with the High vs. Ultra performance numbers we saw in our first Doom 3 GPU review [http://www.anandtech.com/video/showdoc.aspx?i=2146...].

    There's no magic increase in performance if you back down to the High quality setting, so if you're seeing numbers contrary to what I've shown here something fishy is going on and it's not related to memory size.

    For those of you wondering why Doom 3's Ultra Quality mode doesn't require a 512MB video card, keep in mind that the test we're running here is reporting average frame rates. Doom 3's timedemo function doesn't output minimum frame rates, but through actual game play the 512MB card is a bit smoother with the Ultra quality settings enabled (only in Doom 3 however). The difference isn't huge in the scenarios we tested.

    I have no doubt that 512MB boards will make sense sometime down the road, but not paired up with this GPU.

    Take care,
    Anand

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