The importance of video memory

Discussion in 'iMac' started by iKnackwurst, Jun 5, 2012.

  1. iKnackwurst macrumors member

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    Apr 23, 2012
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    Germany
    #1
    Good day,

    I'm planning to buy the top end 27" iMac in the next month (I hope the 2012 iMac has been announced until then) But I am not sure if i should upgrade my video memory.
    Fyi: Currently i own a 13" MBP back from 2009 with 256mb of video memory on the nVidia 9400m.

    Can someone here explain what benefits i would have if i choose the higher configuration with 2GB?

    And maybe how important it is for Video editing or gaming?

    Thanks in advance!
     
  2. kitsunestudios macrumors regular

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    Apr 10, 2012
    #2
    In games, more Video RAM stores textures. You'll be able to play with high quality textures without major slowdowns. 3d pro design apps have less optimized textures, and will use all the video ram you can throw at it. GPU-based rendering will also use the VRAM to help increase render speeds.

    In video and graphic design, the card can store video clips or images as textures for OpenGL accelerated 3d effects and transitions. More video ram means less slow down for longer clips or bigger image files.
     
  3. leman macrumors 604

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    Oct 14, 2008
    #3
    Short answer: don't upgrade. Even for gaming (the only area where the amount of VRAM really matters) the benefit is minuscule.
     
  4. russofris macrumors regular

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    Mar 20, 2012
    #4
    Additional GPU memory typically gives you the following.

    More discrete memory available for textures
    Additional frame buffer memory to reduce the resource cost of using multiple monitors.
    Additional memory for GPGPU/OpenCL applications.

    The three reasons to spring for the additional memory are:
    1: You wish to play games that leverage high resolution textures or use a CAD/CAM program
    2: You use three monitors
    3: Your workflow includes a GPGPU application (think SETI or Folding@home)

    F
     
  5. DeF46 macrumors regular

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    Belgium
    #5
    Good question. I have been taking notes for my next iMac purchase, this is what I have (I don't have sources for all the notes):

    * "Portal 2 tests saw as high as 96% use of the 1G of VRAM." (probably from AnandTech bench)

    * Skyrim HiRes Texture Pack + lots of mods eats up lots of VRAM (because the mods, contrary to the developers, do not bother with limits and will happily give you 4096x4096 textures if that's what you fancy).

    * "Between Shogun, BF3, and Skyrim, (...) modern games that need 1.5GB of VRAM. (...) the 1GB cards collapse due to the use of high resolution textures" also from AnandTech article. edit: linky

    Full quote:

    Personally this time I am not making the mistake twice: I am getting 2GB VRAM.

    I think the upgrade (about 100 € here) is worthwhile, considering I'm buying a computer for at the very least the next two years.
     
  6. Razorhog macrumors 65816

    Razorhog

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    #6
    I'm surprised that there aren't cards with 2.5, 3, or even 4GB VRAM. Maybe there are...
     
  7. kitsunestudios macrumors regular

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    Apr 10, 2012
    #7
    Well, from what I've heard most games still use well under 2GB, and video ram can be pretty expensive. A lot of top-end cards (GeForce 580 and Radeon 7970) do have 3GB more. The top end Quadro Pro has up to 6GB.

    Btw: Thanks for the link DeF46, I was under the impression that most games were still under 1GB. Definitely something to keep in mind when I get a new system. It still seems like 2GB is more than enough for most games out right now.
     
  8. Macman45 macrumors demi-god

    Macman45

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    #8
    If you are not in the video / photo industry, and don't play games, stick with stock (which I believe is still 512MB?) I have a 2GB cram setup but it's for workflow and heavy realtime dual monitor work...Mind you, with an iMac, it's tough to do after purchase so if funds permit, I'd go for the 1GB if possible.
     
  9. DeF46, Jun 5, 2012
    Last edited: Jun 5, 2012

    DeF46 macrumors regular

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    #9
    The AnandTech benchmark I linked above is for the 7870 and 7850, which should be indicative of the 7970M performance if it ends up in the newer iMacs. Hopefully the base model in the 27 inch would be 1GB and the upgrade 2GB.

    edit: well at least I see a Dell Alienware featuring a 2GB 7970M.
     
  10. brucethemoose, Jun 5, 2012
    Last edited: Jun 5, 2012

    brucethemoose macrumors newbie

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    Jan 2, 2012
    #10
    I hail from the lands of OCN (the land of gaming), and am here to debunk the VRAM myth.


    I use a rig with 2 6850s (1GB equivalent VRAM, GPU power just above 7970m) and game at 2560x1440 (27" iMac resolution). I have a ton of Skyrim texture packs/mods installed, play a variety of games, and also do a little CAD/Premiere work on the side.


    1st, If you don't game and don't use more than 2 monitors, 512mb is entirely sufficient.

    2nd, if available, 1GB of RAM paired with the power of the 7970M GPU is enough for gaming. Sure, many games will use more than 1GB with crazy AA schemes if you give them the opportunity, but the only games I've played that could BENEFIT from 2gb are BF3 and Metro 2033. Turn the settings to2xAA or No AA in most of the review's games, and they'll be perfectly happy with 1gb VRAM at 2560x1440 (aka a 27: iMac). I've found that 1gb is perfectly fine, and mobile Pitcarn (the 7970m) isn't powerful enough to reap all the benefits of 2gb VRAM.

    3. Some massive video editing workflows and CAD applications benefit from more than 1gb VRAM. If you're not sure you need 2gb of VRAM for that sort of stuff, you probably don't. If you still think you do, do some digging.




    If you game, given the choice between 512mb and 2gb, pick 2gb. If 1gb is available for alot less $$, pick that instead.


    If you don't game, 512mb is perfectly fine unless you're driving 2 or more 27" displays for video work.




    Also remember, more GPU memory does NOT give you a faster gpu. Having a 4gb or 8gb 7970m over 2gb would make absolutely no difference whatsoever.
     
  11. Mr Rogers macrumors regular

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    Hong Kong
    #11
    AMD 7970m

    According to AMD's website spec's for the 7970m it ships with 2G VRAM, hence, the top end BTO i7 iMac 2012 model as a base card should utilise the base 7970m GPU card at 2G VRAM - a good overall card - and possibly offer an upgrade to 3G VRAM - I think for iMac users that 2G video RAM is more than sufficient for a minimum of 2 years.
     
  12. brucethemoose macrumors newbie

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    #12
    The 7870 uses a 256 bit memory interface, which generally means 1gb, 2gb, and 4gb are the only practical sizes. 3gb is possible with different size memory chips, but very unlikely.

    And remember, the 7970M is an underclocked 7870 or 7850 (idk if they disabled any shaders). In 2 years, 2gb might be useful, but for now, 1gb is fine for this card. Just look at gtx 560 TI or GTX 570 benchmarks for a general performance comparison.
     
  13. iKnackwurst thread starter macrumors member

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    Apr 23, 2012
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    Germany
    #13
    Thanks for all the advice. If the 7970m really has 2GB as standard, and Apple includes it in the next iMac I'd be very happy. Would safe me the longer delivery time for customized Macs :).

    If not, well then i have to face the delivery time.
    From what I've heard so far i think it is the best to spend the money and be on the safe side for the next years.
     
  14. brucethemoose macrumors newbie

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    Jan 2, 2012
    #14

    Meh, I agree, 1gb is fine if you want to save $$$, but 2gb is fine just to be on the safe side.
     
  15. Rodus macrumors 6502a

    Rodus

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    #15
    @brucethemoose, I agree with everything you've said in this thread, I'm running the same GPU setup as you, Xfired OC'd 6850's at 2560x1440 and I'm not having VRAM issues, probably because I don't play BF3 or run crazy AA settings. 1.5GB is nice but most games still will not fully utalize it and probably won't until the next gen consoles are release, by which time most hardcore gamers will have replaced their 1GB cards.
    To echo what others have said, unless you need to run at absolute maximum settings then stock VRAM should be ok, and if you do run at max settings then your GPU (Apple usually underspec and underclock here) will run out of steam long before VRAM is an issue.
     
  16. russofris macrumors regular

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    Mar 20, 2012
    #16
    I think we're at a consensus as to why and when additional video memory is needed. I believe there is a difference of opinion on whether gamers should look to upgrade. We're days away from the 2012 release. I'm going to buy one. Before you do, look at:

    http://support.apple.com/kb/SP576

    And ponder:
    Code:
    Graphics and video support
    21.5-inch models, one of the following:
    NVIDIA GeForce 9400M graphics processor with 256MB of DDR3 SDRAM shared with main memory3
    ATI Radeon HD 4670 graphics processor with 256MB of GDDR3 memory
    27-inch model with dual-core processor, one of the following:
    ATI Radeon HD 4670 graphics processor with 256MB of GDDR3 memory
    ATI Radeon HD 4850 graphics processor with 512MB of GDDR3 memory
    27-inch model with quad-core processor:
    ATI Radeon HD 4850 graphics processor with 512MB of GDDR3 memory
    
    Knowing what you know about the changing game requirements from 2009->2012, if you had bought a Mac 3 years ago which of the graphics options would you have chosen? It's a good question, because it answers the immediate question of which configuration you should choose now if you plan on using your 2012 iMac in 2015.

    Looking at the iMacs since 2008, the amount of video memory seems to double every year.

    Sorry if I'm thinking out loud.

    F
     
  17. unfrostedpoptar macrumors regular

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    Jan 29, 2010
    #17
    I just got a base 27" iMac (512MB) and have two 27" u2711s attached to it and it seems fine. I'm not a gamer and mostly have fairly static programs running. If I was watching a video, it would only be on one of the screens.

    Each 27" monitor is 2560x1440 = 3,686,400. Time 3 -> 11,059,200 pixels.
    If you assume 24-bits per pixel, that's only 32MB. It's going to need more for all the tricks the video needs to do like windows covering other windows and GUI effects, but I can't see how 512MB wouldn't be enough for people who aren't extreme gamers.
     
  18. DeF46, Jun 8, 2012
    Last edited: Jun 8, 2012

    DeF46 macrumors regular

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    #18
    Keeping things relative here, assuming gamers who enjoy gaming on the iMac, how are they going to replace the 1GB card?

    I think with Skyrim's hires texture pack, it's pretty clear that within the next couple years more than 1GB will not be necessary, no, but will certainly be taken advantage of by upcoming games.

    If anything, I noticed when my father played Rage on a VaporX 5770 I bought him with 1GB the textures reload when he turns around sometimes, pretty sure that's due to unloading/loading new textures in memory.

    ----------

    I think that was a great argument put forward in this thread. It's true that the iMac card will very likely not run 2560 full AA on new releases in a couple years after purchase.

    Edit: Technically speaking, afaik, the AA and triple buffers don't use that much memory. So I think the extra 1GB will benefit as games use higher and higher textures. Higher textures are not really more expensive on the GPU, I think.

    Also where AA is concerned, it depends on the games. I prefer to activate AA at 2560 on a RTS / turn by turn game where a min. 25 FPS is sufficient, I would turn it off for action games.

    As for the underclock that's easily solved with tools in Windows. It makes a big difference on my ol' 4850M to go from average 29.4 FPS in DIRT 2 's Benchmark at 2560x1440, up to 35.1 Avg with an overlock that brings to the desktop 4850 speed.

    4850M > 4850 = Texture Fillrate 20.1 GTexel/s > 25.1 GTexel/s

    I've been doing this for two years now with never a blue screen or a freeze.

    In theory, the 7970M should be OC'able similarly to approach or even attain the 7870 desktop speed with the same stability, but it's not the same model so only experience will tell...
     
  19. thekev macrumors 604

    thekev

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    #19
    I'm not sure how much they'd currently benefit you when it comes to video games. NVidia and AMD tend to limit really high vram configurations to workstation models and gpgpu computing nodes in NVidia's case. These tend to carry extremely high margins, and they aren't really suitable for gaming.
     
  20. russofris macrumors regular

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    #20
    Since the amount of VRAM doubles every 12-18 months (somewhere in between the iMac release cycle and Moore's law), you are correct in that it won't 'currently' help much. It will help a bit with next years games, and it will help a ton with the 2014 game lineup.

    Just take a look at the VRAM configs on the 2008->2011 iMacs. Look at how game requirements have changed between 2009 and now (in 2009, 256mb was the norm, and 512 was the upgrade).

    If you plan on owning your iMac for 3 years, and you plan on using it for gaming, you should probably get the upgrade. If you plan on selling in 1-2 years and rolling the funds into a new iMac, or do not plan to game, then don't get the upgrade.

    F
     
  21. thekev macrumors 604

    thekev

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    #21
    It may or may not extend the longevity of the card depending on other factors such as fill rate. They could have just made 2GB standard. It would have made more sense. 256MB wasn't really the norm in 2009. It was the norm for Apple. They've been improving, but sometimes they leave some really oddball configurations in their line.
     
  22. catalyst6 macrumors 6502a

    catalyst6

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    #22
    I actually ordered a 4GB video card for a PC I own. Unless you do a lot of multi-monitor or high-res gaming, or video editing you probably don't need it.

    I actually edit RED raw files in Premiere Pro. Premiere Pro leverages the GPU to help render the editing timeline via Nvidia CUDA. Premiere can actually use more than 4GB of VRAM! This is, of course, supplementary to a large amount of system RAM.

    Keep in mind these are video files that are at minimum 4x larger than 1080p, so the more memory the better.
     
  23. russofris macrumors regular

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    #23
    Since we're talking about iMacs in the iMac forum, and conversing about the potential procurement of a 2012 iMac, the 'norm' that I was referring to was the 'norm for Apple/iMac'.

    I totally accept that there is a diverse and thriving PC ecosystem outside of Apple's offerings, but have always equated the iMac's graphics subsystem to that of high-performance mobile computers, and not their bigger/beefier general purpose PC counterparts which would put the iMac to shame in almost any graphics performance comparison.

    Sorry if my context wasn't clear.

    F
     
  24. thekev macrumors 604

    thekev

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    #24
    I'm probably just in a grumpy mood today, although I didn't mean to come off like that. Even for mobile cards, they do sometimes go kind of bare minimum relative to the computer class. It kind of annoys me when they do things like that. The imac basically shares gpus with gaming laptops, so they're typically my reference when looking at whatever the $2kish imac option is at the time.
     
  25. theSeb macrumors 604

    theSeb

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    #25
    2 GB is the norm for Nvidia 670+ and there are a few 4 GB options. The 640 cards mainly come with 2 GBs with a few 1 GB options.

    AMD 7950 and 7970: most cards seem to come with 3 GB. I can't find a single card on scan.co.uk that does not.

    2 GB seems to be the norm these days (for desktop GPUs anyway)
     

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