6 Gigs of RAM. OSX only shows 4???

[DubbleDuecer]

I did a search when I bought the ram. Showed how to install it. I bought 2 2 gig sticks to go along with my 2 1 gig sticks that came with my mac pro. The search told me to put the 2x2 gigs in riser a in slot 1 and 2, and put the 1x1 sticks in riser b slots 1 and 2. I did this, Vista says I have 6 gigs. I booted up to OSX and it says I have 4 gigs. Under "system Info" it shows that all of riser B is empty. Any ideas?

 

[rikoshay]

First thing: make sure that your RAM has clean contacts & that it's seated fully. Use a pencil eraser to make the contacts on the RAM shiny. Install each card in its slot, then remove & reinsert. You'll be making sure that you'll have good contacts with the socket. DO NOT TOUCH THE CONTACTS. Handle each RAM card by its edges. When each card is fully seated, the 'latches' at each end should click into place. You can see this happen. Once you've done this to each RAM card, THEN you can look for other sources to your problem.

 

[DubbleDuecer]

Ive done that. I installed it and it was fine. Vista showed 6gigs working. Then OSX only showed 4, rebooted in Vista it too showed 4 gigs, shut down took out the b riser, put it right back in and vista showed 6 gigs again. I duno.

 

[Sayer]

Mac OS X is very picky about the RAM you install, getting more and more picky with each major point release e.g. 10.4, 10.5.

I'd exchange the RAM that doesn't show up if its the new RAM. Or if its the old RAM put them in different slots and see if they show up.