Bootcamp (Windows) not using all available memory

GrBear · #1 October 19th, 2007, 09:51 PM

Here's an odd one.. I have a Mac Pro (2x dual core) with 4x512MB and 4x1024MB FB-Dimms (6 gigs ram total). Mac OS X recognizes it as 6 gigs, Windows (under boot camp) only says I have 2 gigs both under XP and Vista.

The memory is installed correctly (as in 2x512MB in slot 1 & 2 and 2x1024MB in slots 3 & 4) on both ram boards.

I did a quick Google on this and couldn't find an answer.

edit: eh, guess it's time to update my sig.. blah..

**fryke** · #2 October 20th, 2007, 02:07 AM

Hm. Try the bigger DIMMs in the lower slots, i.e. 2x1024MB in slots 1&2, take the 512MB DIMMs out, just for testing. Then add them...

artov · #3 October 20th, 2007, 01:47 PM

Are you sure it is not only the case of a 32 bit operating system? As Microsoft says:

Quote:

Operating systems based on Microsoft Windows NT technologies have always provided applications with a flat 32-bit virtual address space that describes 4 gigabytes (GB) of virtual memory. The address space is usually split so that 2 GB of address space is directly accessible to the application and the other 2 GB is only accessible to the Windows executive software.

GrBear · #4 October 20th, 2007, 07:23 PM

I swapped the 512MB FB-Dimms and 1GB FB-Dimm positions on the carriers and XP still only reports 2G of free ram.

I gave up on Vista since its a real dogs breakfast.. nothing to see there other than frustration of being treated as a 2yo asking if I really want to do something. Yeah, I know I can turn all that off. I'd rather have implied security rather than being told if you turn off the hand-holding your OS won't be secure anymore.

Still, I use XP for gaming.. Orange Box specifically Portal, while short, would be my favorite game of the year hands down.

eric2006 · #5 October 20th, 2007, 09:21 PM

Detailed info here:
http://forums.macnn.com/104/alternat...-ram-shows-up/

GrBear · #6 October 20th, 2007, 09:29 PM

That confirms my suspicions, it's a Windows issue.

Thanks!

**fryke** · #7 October 22nd, 2007, 04:41 AM

Apparently it's a combined Apple's BIOS on EFI and Windows issue. Either way: I'd take a look at it again when running Leopard etc. Maybe they've fixed the problem but aren't updating BC for Tiger anymore.