11-07-2010, 01:04 PM

I just installed two 2GB RAM cards into my mac pro, that already had four 512 MB cards in it. My machine is now reading 5 GB instead of 6. Did I do something wrong? The slots are as follows: A1 and A2 512MB card in each, status ok, speed 667 MHz. B1 and B2 512 MB card in each, status empty. A3 and A4 2GB card in each, status ok, speed 667MHz.

So my machine is not reading the B1 and B2 slots, and my speed is still at 667 MHz for all of the cards. Does anyone have any advice for me as I am new at this. Thanks, hope this isn't trivial on here.

11-07-2010, 03:56 PM

Has the machine always read the B slots? And as far as the speeds, the mobo might only support 667mhz speed ram, so it automatically downclocks to the speed it can handle. Or it's running at 667 because it doesnt need to run at 800, 1066, 1333, 1600 etc.

11-07-2010, 05:03 PM

Yes before I installed, it read the 4 slots including the Bs as each having a 512 MB card. I added the 2 new ones in slots 3 and 4, and it picked them up but stopped reading the Bs?

11-07-2010, 06:23 PM

Only things I can think of are:
a) It only supports 5GB (I've never heard of this before).
b) Somehow that RAM might have gotten shocked/something so it's dead.
c) It really has 6GB but 1GB is dedicated to something else. I would look in the Bios if possible (most realistic option).

Other than that, I have no idea.

11-07-2010, 06:54 PM

Don't the ram sticks in the mac pro need to be set in pairs...like 512 on both a1 and b1? I always thought that's what it was setup as?