4GB XMS2 + Vista

[Snapper]

Hi,

Building a new machine, main use being Lightroom/Photoshop. Got a Gigabyte P35-DQ6 mobo for which I've bought 2 x 2 x 1Gb matched pairs of XMS2 memory. Now I've just read in another forum that if you put 4Gb of memory with Windows Vista32 all sorts of horrible things start happening. Which surprised me as Vista32 is supposed to have a 4Gb limit. So I thought I'd ask the memory experts even though, if true it's the fault of the Bill Gates Pension Fund (probably)!

[Yellowbeard]

Nothing horrible will happen with 4gb of memory and a 32bit OS. However, any 32bit OS including Vista and XP, can only address a TOTAL of 4gb of installed system memory. So, the OS allocates address space to the onboard devices first such as the CPU cache, the video card, and anything on the PCI or PCI Express buses. So, after that is done then the OS then leaves the remaining address space for the installed system memory.

So, if you have a 512mb video card for example, you will be able to "see" approximately 3.5gb of system memory as the video card (as well as the CPU cache etc) is allocated address space first.