Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Is 4GB of VRAM overkill for 1080p gaming?

  1. Oct 8, 2014 #1
    I will be upgrading my graphics cards to two Nvidia GeForce GTX 970's in SLI soon, and I was wondering if 4GB of video memory is excessive for gaming at 1920x1080 resolution.

    The newest generation of graphics cards from both AMD and Nvidia were designed to run games on 4K resolution. I only have a 1080p monitor.

    My two GTX 680's (2GB) in SLI sometimes struggle to run games like Crysis 3 and Battlefield 4 on it's maximum settings and resolutions, which is why I am upgrading. I read on another forum that the maximum VRAM consumption of these two games on max detail @1080p is around 2.5GB, is that true?
  2. jcsd
  3. Oct 8, 2014 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    In general, you can never have too much RAM. The old saw, "It's better to have it and not need it, than it is to need it and not have it," applies here, I think.

    You might junk that old 1080p monitor and get a new one with more res. You might get a hot new game which is unplayable w/o the extra memory.

    Of the limited sample of graphics cards I scanned which use the GTX 970 GPU, it's not clear you could get one with less than 4 GB of VRAM anyway.
  4. Oct 8, 2014 #3


    User Avatar

    Staff: Mentor

    No idea what these games need, but my understanding is that the amount of VRAM depends less on the resolution, more on the amount of textures used and data processed.

    My approach was always to buy the best card I could afford at the moment - the better it is, the longer it will last. You are not buying a card that will work with these games, you are buying a card that will work with future releases.
  5. Oct 8, 2014 #4


    User Avatar
    Gold Member

  6. Oct 9, 2014 #5
    One last question, would a PCIe x8 slot bottleneck a single GTX 970 or two of them in SLI?

    And would a Core i7 3770K @4.0 GHz w/16GB RAM also bottleneck a GTX 970 SLI setup?
  7. Oct 9, 2014 #6
    You want two x16 slots for your SLI. Often mobos have one x16 and one x8 slot and in this case, the SLI would run at x8. This setup would still be better than a single card in a x16 slot but it's not as good as it can be.

    The 3770K should be just fine with your SLI setup.
  8. Oct 10, 2014 #7
    The PCIE 3.0 x8 slot has the same bandwidth as a PCIe 2.0 x16 slot.

    I was told by a tech-expert on another forum that the only thing capable of fully saturating the PCI bandwidth is a high-end dual GPU card like Nvidia's Titan Z.
  9. Oct 10, 2014 #8
  10. Oct 11, 2014 #9
    Yeah, i remember reading in a magazine called Maximum PC about how future PCIe 4.0 slots will be capable of 64GB/s of PCI bus data transfer rates instead of the current maximum of 16GB/s.

    This hints at just how powerful future generations of GPU's will be, like Nvidia's "Volta" and "Einstein".
  11. Oct 11, 2014 #10
    IIRC, MaximumPCs most recent Dream Machine (often costing nearly as much as a fairly serious sports car) had 4 of the fastest nVidia boards in SLI and didn't saturate the bus. I suspect that the increase is in preparation for increased usage of PCIe. One example of this is particularly interesting because it addresses the weakest link in bandwidth, that of permanent storage. Apple currently sells some aftermarket PCIe expansion cards to accommodate SSDs which rather humiliate the SATA interface. It's new and they're rather pricey just yet but this application will likely grow and come down in price.
  12. Oct 12, 2014 #11
    SATA still has it's limitations, especially with RAID setups.

    Is the PCIe SSD market going to grow? Those things are blistering fast but very pricey.

    And I assume that the dream machine you're referring to MaximumPC's "large pixel collider" or the LPC?
  13. Oct 13, 2014 #12
  14. Oct 19, 2014 #13
    Yeah, more RAM is good. Downsampling is actually one good method to make games look better (you render at a resolution like 2k or 4k and then downsample the resolution to 1080p) and you need a lot of RAM for that, especially if the games use high quality textures.

    The PS4 has 8GB of VRAM available to it, so developers are probably going to code games that utilize that, so I would probably look at having 4-8 GB of VRAM as a minimum. Your card can offload to system RAM, but it slows things down. You can also use SLI to double the total amount of RAM available to the GPU processors, e.g. buy a card with 4GB of RAM now and then add another in 18 months when it has cheapened.
  15. Oct 19, 2014 #14
    Actually I believe that having more than one GPU does not double the total amount of VRAM, it just means that each graphics card is capable of accessing X amount of memory.
  16. Oct 19, 2014 #15
    Having two video cards in SLI mode does double the amount of video RAM available to drive the monitors on the primary card. However, I think that you are probably referring to the fact that the stream processors on one card do not have direct access to the RAM on the other cards.

    Whether or not it "doubles" your RAM depends on what kind of operation is being performed. If the operation, for example, requires each card to store the same information, then you will see no effective increase in VRAM. The two cards would just mirror the same information. By contrast, if the two cards are running different tasks in parallel, then you could see anywhere from a small effective increase in what is stored in VRAM to a complete doubling of information.

    In CUDA applications, for instance (e.g. calculating physics for a game), you effectively have twice the RAM to work with. The same can be true in split-screen rendering. In alternative-frame rendering (which is the mode commonly employed in video games to run in SLI), you will see much less effective increase in VRAM, perhaps none at all.

    I would say in most video games these days, you are correct that the RAM is simply mirrored completely in SLI mode.
  17. Oct 20, 2014 #16
    @vociferous - It's actually doesn't follow that a video card should have a minimum of 8GB based on the PS4 having 8GB. In the case of a desktop system system ram and graphics ram are most often 2 separate entities, certainly in the case of one employing a PCIe slotted graphics card this is so. Modern PCs generally have 8-12 G system ram plus what the graphics card has.

    In the case of the PS4, if I'm not mistaken, 8GB is the total ram for both system and graphics. There will never be a circumstance when all 8G is being used by a PS4's graphics. As others noted more ram, as much as you can manage, is rarely a bad investment, but while not exactly overkill a 4GB video card, is heavy on headroom at 1080p.

  18. Oct 20, 2014 #17
    Yes, the Playstation 4's memory is shared by both the CPU and GPU.
  19. Nov 14, 2014 #18
    If you're not pushing your resolution over 1080, running an SLI setup is almost wasting money. Almost. You're definitely entering the grey area of compromising cost effectiveness vs performance. If you're wanting to stay with 1080, stick with a big single-slot solution. Cranking up above 1080... that's where SLI begins to shine. Also, even the baddest video card on the market is still hard-pressed to saturate an X16 2.0 slot. I currently run two GTX 760's in SLI along with a 4770K @ 4.9GHz with a 1080 monitor. The only reason I have the extra card is for cranking up AA and antisotropic filtering.
  20. Nov 14, 2014 #19
    To directly answer the OP's question, the more ram the better.
  21. Jan 29, 2015 #20
    If you run out of VRAM all the hell breaks loose. Or at least your game becomes a slide show. Your FPS comes down from what ever it was to somewhere round 2-5.
    If this problem occurs, bring down the AA setting. That takes a lot of VRAM. Do not touch the lately released (while typing this) MSAA setting, since it should not be a resource hog. And leave the AF alone. Instead, ALWAYS max it out.

    What comes to PCI-E 16 or 8. Most motherboards, unless you have some Ultimate Platinum Gaming Extra motherboard and rarely even then, drops the PCI-E down to 8 when in SLI. Don't sweat about it. It's not a biggie. (PCI-E 8 equals to PCI-E gen 2)

    And if you bought the GTX 970's like me, I have some "great" news. They just found a bug in them. If they use more than 3GB VRAM the card comes to it's knees. At the moment nobody knows why (even Nvidia), and even less how to fix it. We are living exciting times...

    EDIT: And to OP, overkill? No. Not with DSR (Dynamic Super Resolution). I've used it only in one game so far, but can say it really makes a difference.
    Last edited: Jan 29, 2015
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook