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: [email protected] > To: [email protected] > 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: [email protected] > [mailto:[email protected]] On Behalf Of Gary VanderMolen > Sent: Thursday, April 29, 2010 9:09 PM > To: [email protected] > 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. > > >
