I have an octo 3.2 GHz 2008 Mac Pro. I have 14 gigs of ram(6x 2gig, 2x 1gig sticks) and they are in the correct order/positions/pairings. My machine would properly show me as having 14gigs of ram for the last 9 months that I've had it however I recently installed windows 7 to one of the hard drives in my machine which proceeded to show me as having 12gigs of ram. When I would go back to OSX it changed to show me as having 12gigs of ram just as Win7 did. When I unplugged all the extra 2gig sticks I had purchased from OWC and powered on, then off and reinstalled the ram, I got the 14gigs to show again in OSX. However, as soon as I went back to Win7 and then back to OSX I was down to 12 gigs. Does anyone else have this issue or know a solution? Any assistance would be greatly appreciated as I am out of ideas and am tired of opening my machine up over and over again.
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RAM disappearing on my 2008 Mac Pro
- Thread starter codemonkey86
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I'm just using bootcamp, not vm or fusion. i can get the ram back by pulling the sticks out and reinstalling them. I then get all 14 gigs until I jump into Win7
My problem was similar but not identical.
After returning home from vacation, I started my Mac Pro and the ram amount was wrong.
I cleaned the Mac Pro and when I reassembled the ram risers and modules, I started getting all sorts of wrong ram amounts reported.
I kept taking them out and carefully cleaning the contacts and slots on the risers and on the motherboard and eventually the ram amount reported normally.
It might just be a little bit of dust or incorrectly seated modules rather than anything to do with the windows 7 install.
Thats what I thought too, however after reassembling the RAM and getting back to 14 gigs I can't get it to disappear and it can stay for days(avoided Win7 for a few days). However I can trigger the change to 12 gigs simply by booting into Win7. As far as I have been able to tell booting into Win7 causes one of my pairs of 2 gig sticks to show as 1 gig sticks(system Profiler).
I had RAM problems like this that I was able to cure (so far) by re-seating the graphics card and RAM. Odd I know, but when you're troubleshooting, it's better to try everything. 
If bootcamp is reporting wrong amount, it should not affect OSX if it was merely a bootcamp / driver issue.
Do you get any errors under memory in system profiler? Or is it all reporting as ok?
Do you get any errors under memory in system profiler? Or is it all reporting as ok?
I also have win 7 (32 bit) on bootcamp on my mac pro but the win 7 is on a separate hard drive, and I have not been able to replicate your issue.
I do know that in win 7 it only sees 3 of my 16 gb of ram, but it always goes back to showing 16 gb when I return to osx.
32bit is capped at 4gigs of RAM however Windows tends to show what is available and "hides" the rest saved for the system such as in your case you see 3gigs when in reality 4 are being used. I am running 64bit Win7 which along with OSX shows 12gigs of RAM(14 gigs in OSX only after opening the case up and playing around)
Attached is a screenshot of my sys profiler. It shows 2 of my 2 gig sticks as being 1 gig sticks. I get this to show them as 2 gig sticks as it should and the 14 total gigs only after opening my case and going through what I outlined in my initial post.
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