Missing RAM in XP

[tnbriggs]

I just installed an additional 2 gb of RAM in my Mac Pro 2.66 quad, so with the original 1 gb I've got 3 gb and OSX lists it such. 2-512 mb in riser b, slots 1 & 2, 2-1gb in riser a, slots 1 & 2.

XP only reports 1.99 gb. Not that I really need it in XP, but curious why the difference. I know XP has a 4 gb limit, but 3 is still less than 4. Is it something about the way the RAM is installed, or a OSX driver issue?

Thanks.

[zarmanto]

I just did some research into this, and it seems that there is more misinformation out there, then actual information. It seems that the 2GB limit is somehow related to 32-bit versions of Windows running on BootCamp -- if you go from a Mac to a standard PC running the same software, you will probably find yourself with a maximum of 4GB, (or in some cases, some oddball number between 2.5GB and 3GB) whereas if you go from the 32-bit version of Windows to the 64-bit version of Windows (presumably on any hardware) then the upper limit is theoretically pushed to 16 terabytes. I think the most interesting thread on this topic which I read was probably this recent one over in Apple's own support forum: Boot Camp 2 GB RAM limit (http://discussions.apple.com/thread.jspa?messageID=6383859)

[barmajan]

try to use 64-bit version of windows xp