Does SLI make full use of video RAM?

Discussion in 'Graphics Cards' started by Petros, Feb 26, 2007.

  1. Petros

    Petros Thief IV

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    After an enjoyable and spirited discussion in another thread, I got to thinking about my future upgrade. Two questions for SLI experts:

    If I buy a 320MB 8800GTS, then purchase another down the road, will a game behave as if it has 640MB of RAM to work with (say, running F.E.A.R. at ridiculous resolutions), or whill it drop off as if it were a lowly 320?

    By the way, I think it's complete hooey that your second monitor gets disabled when in SLI mode.
     
    Last edited: Feb 26, 2007
  2. trainmaster77

    trainmaster77 Moderator Political User Folding Team

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    why is that hooey? you could always hack the resolution ..so that you could use both monitors ...for instance ...if you were using 2 20.1" monitors @ 1600x1200 res .... you could make the rez 3200x1200 ...and the middle would be between the 2 monitors ofcourse ...or you could even get fancy and modify the lcd panel bezel and stick the 2 panels together heh.

    i realize thats not what you are after ..and sli is designed for gaming and video intensive applications such as GIS or CAD ... you can turn it on/off as you see fit as well.

    so when you are doing your word processing or net surfing you are able to turn SLI off and use both monitors again.
     
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  3. LeeJend

    LeeJend Moderator

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    Mostly no. Depending on which method of load sharing is optimum for a given game you will either see 320 MB or maybe a little more.

    If you are using alternate frame sli each card will have to load all of the textures. That means you only get 320 MB. If the game uses split frame each card might only have half the screens worth of textures loaded. Theoretically this will increase your memory over 340. This falls apart when you do something like look at your feet and then straight up. Now all the textures must be loaded. Because of this the SLI controller sends the texture info to both video cards negating the added memory.

    If you're going 8800 I'd spend the extra $50-70 and get the 640 Mb. Or go for the 8800 GTX and forget the SLI. The SLI performance boost just isn't consistent enough to justify buying 2 boards instead of one better board. It all hinges on you taking the risk of there being an identical card available at a much lower price a year latter.

    I did a cost benefit trade on dual cards 2 years ago and decided it was marginal at best. Now that I have seen that getting a second matching card a year later is between hard and impossible I conside SLI a bad idea.
     
  4. Petros

    Petros Thief IV

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    Thank you trainmaster77 and LeeJend! Reps around! Except for LeeJend, because I have to spread rep before giving it again. 8800GTX (or comparable ATI part when it hits the market) it is!