It depends on what the chipset can support. If you have 4GB installed but the chipset supports addressing up to 8GB, then that leaves 4GB of address space that can be used to map the video memory (and others) into. It is not necessary to map the video memory into actual memory--just within the supported address space.
That all assumes that you are running a 64-bit version of Windows. If you're running 32-bit, then everything has to map into the 4GB space. > -----Original Message----- > From: hardware-boun...@hardwaregroup.com [mailto:hardware- > boun...@hardwaregroup.com] On Behalf Of Bobby Heid > Sent: Friday, April 30, 2010 3:56 PM > To: hardware@hardwaregroup.com > Subject: Re: [H] Win7 Ent 32-bit vs 64-bit? > > Well, it does sort of sound like that. I have Win 7 ultimate with 6GB RAM. > When I right-click on My Computer and select properties, it says I have > 6.0GB. On my work machine (4GB RAM) with XP and 2 graphic cards, it says I > have about 2.89GB RAM. > > Bobby > > -----Original Message----- > From: hardware-boun...@hardwaregroup.com > [mailto:hardware-boun...@hardwaregroup.com] On Behalf Of Bino Gopal > Sent: Friday, April 30, 2010 4:49 PM > To: hardware@hardwaregroup.com > Subject: Re: [H] Win7 Ent 32-bit vs 64-bit? > > > But from the MS article: > > > > Note When the physical RAM that is installed on a computer equals the > address space that is supported by the chipset, the total system memory > that is available to the operating system is always less than the physical RAM > that is installed. For example, consider a computer that has an Intel 975X > chipset that supports 8 GB of address space. If you install 8 GB of RAM, the > system memory that is available to the operating system will be reduced by > the PCI configuration requirements. In this scenario, PCI configuration > requirements reduce the memory that is available to the operating system > by an amount that is between approximately 200 MB and approximately 1 > GB. The reduction depends on the configuration. > > > > So doesn't that imply that based on the fact that I only have 4GB, I'll still be > short some memory, unlike what some others said? Or to put it another > way, like Gary said, what will the devices map into since they can't map to > thin air (and apparently they still need to map). > > > And to put a further point on it, since the video card is a MMIO (memory- > mapped I/O) device, I assume it'll take memory away from the max 4GB too. > So the moral of the story is that sure I can upgrade to 64-bit Win7, but if I > don't put more than 4GB of memory in the system, I should end up with > exactly the same amount of memory as with 32-bit Win7 right?! > > > > Now, apps running faster is a whole 'nother reason and definitely worth > doing it for that! ;) > > > BINO > > > > > From: bh...@sc.rr.com > > To: hardware@hardwaregroup.com > > Date: Thu, 29 Apr 2010 22:32:12 -0400 > > Subject: Re: [H] Win7 Ent 32-bit vs 64-bit? > > > > It maps into the address space of whatever the 64-bit address space is > > (8 terabytes or something like that). When you have a 32-bit OS, the > > address space is only 4GB, the system maps in the hardware memory > > (BIOS, graphics card RAM, etc.) space from the top of the address > > space down. That is why you get between about 3-3.5GB of actual RAM > > when you have 4GB RAM on a 32-bit system. I know I'm not explaining this > well, so take a look here: > > > > > http://www.codinghorror.com/blog/2007/03/dude-wheres-my-4-gigabytes- > of-ram.h > > tml > > and > > http://support.microsoft.com/kb/929605 > > > > Bobby > > > > > > > > -----Original Message----- > > From: hardware-boun...@hardwaregroup.com > > [mailto:hardware-boun...@hardwaregroup.com] On Behalf Of Gary > > VanderMolen > > Sent: Thursday, April 29, 2010 9:09 PM > > To: hardware@hardwaregroup.com > > Subject: Re: [H] Win7 Ent 32-bit vs 64-bit? > > > > So what will they map into instead? As far as I know, the video has to > > map into RAM, regardless if the OS is 32-bit or 64-bit. > > > > Gary VanderMolen, Microsoft MVP (Mail) > > > > > > -----Original Message----- > > From: Bobby Heid > > > > > > IIRC, the BIOS and video RAM will not have to map into the 4GB address > space > > (in 64-bit). He will have the whole address space for RAM. > > > > > > > >
