2GB RAM reads as 1GB RAM

[lifeprods]

Hello mac friends,

I just added a pair of Kingston 2GB FB DIMM PC2 6400 sticks of RAM to my Mac Pro 8-core on top of the two 1GB RAM sticks that the computer came with. I was expecting a total of 6 GB of RAM but when I go to computer info it says I only have 4GB which means that the new Kingston sticks are reading as 1GB each instead of 2GB.

Is this bad memory or am I missing something?

 

[BlueRevolution]

It's possible that one of the sticks is not seated properly. Run Hardware Test from your system's restore disks and see if it registers the memory properly.

 

[eddietr]

You can also check system profiler -> memory to make sure the RAM in seated in the correct banks.

 

[BlueRevolution]

Oh yeah... forgot about the easy way.

 

[lifeprods]

The computer is reading all four sticks as 1GB DDR2 FB-DIMM 800 MHz Status - OK

So no, they are all seated properly. But thanks. Any other ideas?

 

[eddietr]

The computer is reading all four sticks as 1GB DDR2 FB-DIMM 800 MHz Status - OK

So no, they are all seated properly. But thanks. Any other ideas?

I assume you moved the factory 1GB DIMM from the lower board to the upper board and then added the new ones as a pair to the lower riser?

 

[JediMeister]

Mac Pros in any configuration require matched pairs of memory to be on the same riser. So the 2 GB sticks should be on the same board, as should the 1 GB DIMMs. Consult pages 1 and 2 of the Mac Pro memory replacement guide in PDF form here and make sure you have placed the RAM correctly.

 

[lifeprods]

Thanks JediMeister!

That was the problem. Since the stock RAM was split between the two racks I just assumed I would add the new RAM the same way. I went ahead and moved the RAM around like you said and now I have my full 6GBs.

yeah!

From Happy Mac Owner!!