How much VRAM does an external 1680x1050 display use?

Discussion in 'MacBook Pro' started by aliquis-, Aug 14, 2007.

  1. aliquis- macrumors 6502a

    May 20, 2007
    Is it 1680x1050x3 byes? ((1 680 * 1 050 * 3) / 1 024) / 1 024 = 5.04684448 MB? Is it dubble buffered so it uses 10MB? I read that with a 30" ACD one would use 128MB/screen on barefeats, is it always that way? So will a 20" external display maybe split the 128MB vram in the MBP?

    Bad Apple, bad.
    Decent software, nice cases, ****** computers.
  2. kolax macrumors G3

    Mar 20, 2007
    Bad Apple? **** computers?

    Care to explain why you are saying that?
  3. other macrumors 6502

    Aug 18, 2005
    I believe the VRAM is just split between the screens, no matter what. Don't quote me on that though.

    And aliquis is always bashing Apple, on all forums he's active on. I don't really disagree with what he's saying, but if he wants to ask for help on a forum full of Apple fanboys, maybe it's not a smart move. :)
  4. aliquis- thread starter macrumors 6502a

    May 20, 2007
    Because they don't balance the specs as I would like. I like to support Apple for what they are doing and I'd very much appreciate if there where more competition, different and innovative ideas in this area (now when be, amiga, atari, ... are gone) but I hate the lock in and the decisions they force on me. I could do quite well with FreeBSD + KDE but I've wanted a mac for so many years (7?) because then you can use some commercial apps aswell and know that things works. But I don't wanna stand up to unlimited amounts of **** either.
  5. aliquis- thread starter macrumors 6502a

    May 20, 2007
    Ok, that's weird, I would suppose windows no matter which screen they where one just used some vram and that each screen just took whatever they needed for the actual display + eventual buffer. That makes 128MB even worse because then if you run a few windows at one of the screens they might not fit within those 64MB anyway (Well, that will probably require like 10+ fullscreen size windows but anway =P)

    Cool that you seem to know me, I just registred on some other international ones but maybe you know me from the swedish one =P
    It's just that I have no work and therefor not unlimited amounts of cash. I want a mac but I know how to get a hack working and I'm not very intrested in beeing force feed very expensive CPUs I don't need due to Apples crappy hardware decisions, that's all :)

    You might be correct, but then again, the worst Apple fanboys doesn't know much about anything anyway so they wont be of much help :), I'd rather get some help from someone similair anyway ;) Someone I can trust :D

    It's like calling Apple and ask if 128MB will be enough, then I would get "Yeah! Sure it will!", but if I instead asked if 256MB would be much better I would get "Yeah, much faster!" instead ...
    Like the guy who posted a flickr image where his dad had e-mailed "Steve" and where arguing that their 15 days old iMac 20" G5 which they had saved money for for two years where already outdated when the Core Duos arrived and "he" answered that it was a great machine and would last for years.
    It is a great machine, and it runs PPC apps faster, of which there where plenty, and it's 64 bit, and so on, so it wasn't a bad buy, he might even have got a better panel, but it's still a little lame as an answer. I would hate if something like that happened to me but I'm intelligent enough to check up rumors and release dates before.
  6. Zel macrumors regular

    Jul 7, 2007
    every screen takes its number of pixels times 32 bits

    a 1680x1024 blank desktop would need therefore 6.6 megabytes of videoram

    put a fullscreen program on it and it doubles. photoshop can fill two full screens, so it eats more.

    it's about how you use it. I suggest you just go use it and quit worrying about how the technical wizards make it happen.
  7. other macrumors 6502

    Aug 18, 2005
    Unfortunately, I can't find any reliable sources about this. I've just read it a couple of times on different forums. Here's an old, old, thread about it:

    I haven't read anything specific about the MBP though, but OS X probably handles all this stuff in the same way.

    It's silly, indeed. Kind of like how they still equip the low-end MacBook and Mac Mini with combo drives.
  8. Don Bagles macrumors regular

    Jul 24, 2007
    If the MacBook Pro's lid is closed, and an external monitor is plugged in, does it get all the VRAM power for itself?
  9. aliquis- thread starter macrumors 6502a

    May 20, 2007
    Yeah but I can't decide if I should go with 128MB 2.2GHz MBP or 256MB 2.4GHz.

    I know 128MB vram isn't worth the insane amount of money Apple ask for it because they also bundle it with 200MHz of worthless CPU power and 40GB hdd but that's the only option I have.

    I want to use two screens because TN-panels are inferior and I want to have a 20" IPS for better image quality, but I'm affraid I will lose something from the 128MB vram one. Also I know it's not perfect for gaming, thought the 8600m GT and OS X aren't either so a real gaming desktop is the better option anyway.. But I'd rather not get another computer aswell.

    Another option is to run the MBP with the lid closed and only use the external screen, that way I won't need much more vram thought.

    Anyway you are 100% sure vram isn't split between screens? Because in rob arts barefeats test he says that the 256MB modell might be better for 30" ACD since it will get 128MB of vram.

    Apple support people doesn't know the answer....

    Could anyone using two screens check using OpenGL Driver Monitor (add the parameter for how much graphics memory is under use and boot one time with only internal screen and another with external or something), the tool is in the graphics applications of xcode.
  10. aliquis- thread starter macrumors 6502a

    May 20, 2007
    I was even suggested by the support guy to get ADC Student on a friend later on instead of I wanted to wait for the next rev. But what says that one will have 256MB? Maybe it only gets penryn chips ...

    I'm sure that if I did paid the extra 540 dollars for my 128MB they would ship the next rev with that as standard ...

    Another alternative I've been thinking about is letting them eat their own **** by staying with 128MB and then Leopard is released see if that gets hacked aswell and just order a PC desktop which is good enough for gaming and install OS X on that aswell. That way I do get my gaming ability without getting screwed.
  11. UrsaMajor macrumors regular

    Jan 4, 2007
    I thought ACD ran over 1920x1080 (1080p), which would be why you'd need higher specs.
  12. aliquis- thread starter macrumors 6502a

    May 20, 2007
    The Apple support guy didn't even seemed sure if one could close the lid, even thought I was quite sure one could. And then I called support instead of Apple Store because I guessed they where better trained, maybe I should try to get a work there, can't be that high demands ..

    I would assume all vram would go to the other screen, but I'm not sure and I doubt Apple can answer me.

    Someone better just try it with the opengl driver monitor part of xcode instead. View the graphics memory parameter and test with one screen, two screens and one with closed lid and tell me the usage after each boot or something.
  13. aliquis- thread starter macrumors 6502a

    May 20, 2007
    128MB card/computer can only drive up to 1920x1080 or how does that makes sense?
  14. aliquis- thread starter macrumors 6502a

    May 20, 2007
    Imho I would belive having people:
    1) Feeling happy with their purchase.
    2) Belive that Apple machines are well speced at good prices.
    3) Sell more machines due to better specs.

    is more worth than:
    4) Get better margins on the few machines sold.

    But maybe not since the average Apple buyer probably doesn't understand better and just get whatever they give him/her and belive it's good, or aren't intrested in a mac in the first place.

    Also I think that having the option to let the customer get Windows with there machine and market it like that would help with their sales aswell, since many people probably doesn't know that they can also run Windows. I'd hate if that happened and I think it's retarded to buy a mac to run Windows, but it would probably help with their sales ;D
  15. mkrishnan Moderator emeritus


    Jan 9, 2004
    Grand Rapids, MI, USA
    Diatribe aside, it really depends on what is being done... there's no hard "requirement" of VRAM, at least not one that isn't far, far less than the available VRAM (like the 10MB you cited). Once you have that much, the computer can make do. But if it is able to, it will use more VRAM to do video effects (all the ripples and genie effects and so on), and also cache menu representations, overlapping windows, and so on. You may have a 1680x1050 screen with 6-10 times that many pixels worth of windows when you lay all the windows side by side. So the computer can use 6-10 that much video memory storing representations of all that, if its available.

    For the most part, though, the big limiter is what you'll do and what software you'll do it with. You can see that, even if you're at 6-10x the 5-10MB you said you need, you're probably fine. But it's a different story if you're using Aperture or Final Cut or iMovie or another program that wants to do its processing in video memory also. Those programs will be far faster when they have video ram to use. And they can often make use of that entire 256MB whether or not you've got a second external display going.

    Likewise, if you're doing 3D modeling or playing a 3D game, it isn't the pixels on the screen -- it's the 3D elements that are being rendered, which means you can benefit from much more RAM than the 10MB that a screen representation might require.

    So in other words, you might be very fine with 128MB (or even 64MB) if you're using typical low stress apps on the internal screen and an external screen. If you're demanding of a video application, though, you could probably use 256MB and even 512MB if it were available.
  16. aliquis- thread starter macrumors 6502a

    May 20, 2007
    So it won't have a problem to draw Windows even if it runs out of vram but will just redraw them each time? Or will it use TurboCache and store them in system ram instead and fetch them when needed? I guess that is faster than redrawing them but puts more load on the already a little to slow memory (DDR2 isn't that much faster than DDR, and it's only 667MHz compared to what? 1066? On desktops, and all CPUs are dual core now so they would have wanted twice the old memory bw.)

    If the VRAM is split in two for each screen then the 1680x1050 screen will get 64MB of vram and use 7MB/screen if it's really 4 and not 3 bytes/pixel. I guess that is ok aslong as I only hold 2D-stuff, but sort of lame anyway.
    For gaming a PC-desktop worth $500+ makes more sense thought, an ATI X1950 XT/Pro will beat the 8600m GT easily anyway. But what about the rest I'm missing? Also if 256MB vram can hold me above the water for a year more or so I get a better PC desktop.

    I have no idea how much vram those apps use. ATM using OS X, Adium, xchat, Safari, X-lite and Textedit on a 1024x768 screen only I use 46MB vram. For heavier usage I could close the laptop lid thought. Still lame, I hate Apple. Atleast I can be happy I won't buy Leopard ;), but that's not much for revenge, I wouldn't do it anyway ;D

    Oh, decisions decisions, this suck. I will come back once I've tried higher res.
  17. aliquis- thread starter macrumors 6502a

    May 20, 2007
    Tested some more, MB in this case means 1.000.000 bytes because it was easier to see and I don't wanna recalculate them. Therefor 128 real MB is 134 SI-MB ;D

    vram usages in os x 10.4.8:
    Adium, Safari, x-lite, x-chat, textedit, itunes
    1280x1024 55 MB

    1600x1200 65MB

    1920x1080 69MB

    But there is always turbocache aswell... I don't know what to do :(

    I'd rather get a Nikon D40 than some vram, but.. What if I change my mind? ;/ Also one can always get more money, but for me they come slow =P
  18. jf8 macrumors regular

    Aug 8, 2007

    video RAM is only "assigned" to a screen for its framebuffer. That is, if closing the lid will disable the screen in the OS (as it does), the RAM that screen is using will be deallocated.

    That gives you about 7.1 megabytes for a 1920x1080x32bpp framebuffer.

    Any other video memory being used is for textures, caches, overlays, etc. and is allocated as needed. I'm not sure how Mac OS X allocates video RAM (are all loaded elements constantly in video RAM, or can they be paged in and out depending on whether they are onscreen/active?), but it has no problem running 1680x1050 and 1280x800 on the (artificially limited by Apple at 64MB) shared memory of the GMA 950, with a decent amount of programs open.
    (Windows Vista manages with low video RAM usage while running Aero as well)
  19. aliquis- thread starter macrumors 6502a

    May 20, 2007
    Glad to hear that, I still know 2.2GHz is the better option but I still don't know what I shall do :(

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