14GB upgrade only shows as 12GB

[Julien]

My Mac Pro (3,1) came with 2GB and have upgraded in the past with 8GB for 10GB (no problem). I just bought a 4GB RAM set but it only shows as 12GB. I thought the RAM was defective and had it replaced but still have the same problem. I have it set up as follows. Riser A 2GB+2GB, 2GB+2GB: Riser B 2GB+2GB, 1GB+1GB. This follows the Mac Pro install chart.

Is there a problem using 1GB (2) RAM on Riser B with 2GB RAM on Riser A (it worked fine with 10GB)? Is it not possible to show 14GB because of this?

 

[westrock2000]

In "About This Mac", what does the graphical representation if the memory slots show? Does it match up to physical install?

 

[pastrychef]

Those riser cards can be a bit temperamental. Try reinserting them a few times and try cleaning the contacts on the edge of the riser cards with a pencil eraser (remember to clean off debris left by the eraser).

 

[Julien]

In "About This Mac", what does the graphical representation if the memory slots show? Does it match up to physical install?

No, it should be 2GB & 2GB in Riser B slots 1&2.

Those riser cards can be a bit temperamental. Try reinserting them a few times and try cleaning the contacts on the edge of the riser cards with a pencil eraser (remember to clean off debris left by the eraser).

I have swapped changed RAM on Riser B and checked/reinserted many times. I will try moving the new RAM to Riser A and see if it shows up 4GB instead of 2GB.

 

[NOTNlCE]

Had a similar problem a little while ago while mixing RAM speeds (something that's advised against, but whatever) - My solution was to mix the pairs up. The pairing on the '08s has a lot to do with how the RAM is recognized. I would move it into every configuration you can, even if it means swapping RAM on the risers. Also, check the dust around or on the risers, I had a small particle stuck on the connector and it was preventing any RAM from being recognized properly on that riser. A nice can of compressed air or a very gentle air compressor can take care of that. Good luck to you.
-N

 

[netkas]

Have an issue with one of 2gb (config 1,1,1,1,2,2,2,2) planks being overheating and disabled by efi after reboot. So on cold(literally !) boot I have 12 gb, after some work and reboot - 10 gb.

maybe ur's overheats too ?

 

[jaxhunter]

I once had a set of RAM sticks from Kingston that said 2GB Kit on the side of each stick; they were a matched pair of 1GB sticks that came as part of a 2GB kit. Kingston apparently thought they were funny...