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32 bit vs 64 bit: How it relates to video cards

Discussion in 'Graphics Cards' started by Mussels, Apr 15, 2009.

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  1. Techtu

    Techtu

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    Mussels - How about updating the original post to include some new figures for example, 1.5/2Gb video cards. Surely these effect the amount of usable ram?
  2. Mussels

    Mussels Moderprator Staff Member

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    DX10 and 11 dont duplicate the ram, so no, it wont be a problem at all. 4GB is still enough for every game these days.


    the rest of your questions are better off asked in another thread, probably here System Builder's Advice



    I think everyone gets the hang of it now. anyone using a 2GB video card in DX9 games in XP 32 bit, is gunna get what they deserve...
    Last edited: Nov 11, 2010
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  3. Techtu

    Techtu

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    Haha... yeah it's pretty obvious come to think of it now :roll:
  4. Rolano New Member

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    Mussels, I think you don't have full understanding of address space mapping and Windows memory model.

    For 32bit Windows, due to linear memory model only 4GB space is addressable.
    Upper part is taken by kernel (mostly API functions mapping) and then goes down by each device drivers mapping their supported hardware IO into 32 bit address space. Video driver is one of them.

    Physical memory is MAPPED into system address space for application use. Video memory is also directly MAPPED to kernel address space, it DOES NOT use physical RAM for it. Its Windows Vista and 7 Aero interface thing that does video frame buffer copy of application window like a texture because it is implemented so.

    Video driver max mapped address space window can be 256MB if i remember correctly and there are some nuances in how kernel memory can be mapped by drivers. Also this kernel and driver memory mapping is always present in all threads so that is why in 32 bit systems with video card with more than 256MB memory maximum usable physical RAM to Windows (without special technique like PAE) can be 3.25 GB, but if other drivers map their portion of kernel memory "badly", you can get down to worst case of 2GB of useful physical memory.

    Now about individual applications. In 32 bit Windows every application gets up to 2GB (3GB with -3GB flag) user space of these max usable 3.25 physical memory for their use. Much of it is same physical memory shared by several applications by using same DLLs.

    In 64 bit Windows, 32 bit applications behave exactly the same way as in 32 bit and have exact same limitations as in 32 bit Windows.

    For 64 bit applications there are several changes:
    1. Kernel system space and driver mappings now take place in upper 8 TB (8 terabytes because current CPUs use only 48 bit physical address lines) of address space, so maximum useful physical memory is 8TB - kernel and driver needs.
    2. Normal applications still get 2GB of user space.
    3. Applications with -3GB flag get full 4GB user space.

    So that is why 32 bit system without special techniques (PAE, ramdisk, etc) can only use 3.25-3.5GB of physical RAM, and 64 bit can use full amount of physical RAM (because no system can have 8TB of physical RAM today).

    I hope this helps to clear things up.
    AlienIsGOD, W1zzard and mauriek say thanks.
  5. Mussels

    Mussels Moderprator Staff Member

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    i certainly DONT understand all of it.

    the whole point of this was to bring everyone out who does understand it, or parts of it, and get all that knowledge together since no one seemed to have a clue about it.


    All i know for fact is that 32 bit OS's are a limitation to many modern games, and a 64 bit OS with LAA applications can alleviate that - the rest of this is trying to figure out why that is (which is hard with so little information available on the internet and contradicting opinions), and getting people to at least realise there IS an issue, even if they dont understand it completely.


    thanks for providing more information, i'm sure people will read it and appreciate it.
  6. Rolano New Member

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    Yeah, nice point about making people informed about operating system they use.

    There is very nice blog detailing how Windows internals work. Here are some useful links for this discussion from there:

    http://blogs.technet.com/b/markrussinovich/archive/2008/07/21/3092070.aspx
    http://blogs.technet.com/b/markrussinovich/archive/2008/11/17/3155406.aspx

    Added:
    It seems, I also have made some mistakes in my previous post, so please read the links I provided for full picture, the info there is guaranteed to be correct.
    Last edited: Nov 23, 2010
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  7. Ulysses New Member

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    Interesting thread, but it certainly does *not* work the way it's described in the 1st post.
    I still have windows XP (32bit) :eek:, and even though I have a 2GB 6950 windows is still able to manage 3.5G (it only "wastes" 0.5G for I/O space). Makes me wonder: is it making use of the video card's 2G ???
  8. Bo$$

    Bo$$ Lab Extraordinaire

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    with your kind of system i would be using seven because it has dx10 and 11 support unlike XP
  9. sliderider

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    In a 32 bit system you don't technically have 4gb RAM. You can install that much, but 3.19GB or something like that is all that is seen by the OS. Anything above that is wasted which is why most systems sold today with a 32 bit OS installed come with 3GB RAM.

    You should have more than that for gaming, though, because even though a particular game might not see anything above 2GB, overhead penalties from the OS are reduced. How many times have you experienced slowdowns while playing because Windows needed to access the pagefile? It's hard for your game to import data from the hard drive with all that pagefile work going on and still maintain a seamless display. These days with people with gaming rigs with huge memory configurations there is virtually no pagefile access, but for those of us lower down on the foodchain it can still get to be a problem.
  10. Mussels

    Mussels Moderprator Staff Member

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    no, in a 32 bit OS its not possible to use that.


    32 bit apps in a 32 bit OS only get 2GB address space total, so there is no way you can use all 2GB of video ram (unless your app uses 0MB of ram)
  11. sliderider

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    Ditto. 7 doesn't suffer the performance penalties that Vista did, either. There's no longer any reason to still be using XP unless you have mission critical apps that actually require it, like some businesses do. Home users should move to 7 and skip Vista and they should be upgrading to x64.
  12. sliderider

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    crazyeyes posted some charts in another thread that showed the amount of VRAM that some games were maxing out at. The only one I remember clearly was Oblivion and that game was maxing out at 600megs of VRAM usage with all the bells and whistles turned on. Games have advanced a lot since then so VRAM usage has to be pushing the limits of a 1GB card by now if it hasn't already surpassed it. When 28nm hits, I wouldn't be surprised to see more cards with more than 1gb installed than there are now. 1.5gb will probably be the minimum for anyone who wants to play games with any sort of eye candy turned on.
  13. Ulysses New Member

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    There has to be some mechanism for applications to use VRAM greater than 256 megs, because that's all that gets allocated in the memory address space... (e.g. XP32bits: E0000000-EFFFFFFF and yes I know I do need to go 7 to get DX11 :p)
    I am not sure the articles quoted are relevant to games running in full screen mode, especially the part about XP having to duplicate video stuff into system RAM: sounds too dumb to be true, even for MS...
  14. Bo$$

    Bo$$ Lab Extraordinaire

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    well read the links on the OP, the inbuilt thing may not be reporting correctly
  15. Ulysses New Member

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    That reasoning is a bit strange... if Windows didn't know for itself where things were in memory, how could anything work :wtf: So yes, the windows system memory report has more credibility than some web article :rolleyes:
    Edit: besides, the article http://blogs.technet.com/b/markrussinovich/archive/2008/07/21/3092070.aspx states that under 7x86 each 1GB card is "only" being mapped for 256MB each, which seems consistent with my findings under XPx86 ;)
    Last edited: Jan 22, 2011
  16. Mussels

    Mussels Moderprator Staff Member

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    from what i've gathered, thats the minimum amount reserved.


    256MB video memory + 256MB reserved system memory (for the mapping) adds up nicely with the 3.5GB usable memory most people see in a 32 bit OS with 4GB of ram


    obviously more can be used, unless you think that only 256MB of VRAM is used with any game.
  17. JayzeBlueshark New Member

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    wow! nice info muss.. but 64 bit OS is compatible with any type of CPU unit? like Core 2 Duo, Dual core, quad core, etc.?

    sorry for the duplicated post.. my internet connection wasn't respond and that is why..
    how to delete that previous post? ..sorry.. i'm in a hurry..
    Last edited: Apr 13, 2011
  18. Mussels

    Mussels Moderprator Staff Member

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    i deleted your duplicate post, but i still dont understand the question you're trying to ask
  19. 95Viper

    95Viper

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    I believe he's trying to ask, if all of the CPUs he listed(plus etc.) are 64bit OS capable.
  20. Mussels

    Mussels Moderprator Staff Member

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    oh. well this really isnt the place to find that, CPU-Z can tell you on any working system, and google can find out for any other. All modern CPU's are 64 bit.
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  21. Delova

    Delova New Member

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    Nice Info Mussels !! Thanks very much !! [​IMG]
  22. Wrigleyvillain

    Wrigleyvillain PTFO or GTFO

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    Yeah the guy's actually good for something now and then! :p
  23. Ray_Rogers2109

    Ray_Rogers2109 New Member

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    So for when the computer I'm building is fully finished will be using 64-bit operating system, 8GB system RAM and a 2GB GPU. Can I still use the 4GB application/exe patcher? Would it make a difference especially for games?
  24. Mussels

    Mussels Moderprator Staff Member

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    yes. thats the situation its designed for.
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  25. EarthDog

    EarthDog

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    4GB here.. sitting with 2.735GB Free and 1.5GB GPU. 2.7+1.5=4.2GB... HUH? What did I miss?

    W764

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