Memory missing from system properties

[gios]

I'm using a Mac Pro (desktop) but running it exclusively in Windows XP 64-bit. Until recently, all 16 GB of RAM was working correctly. Now however only 8 GB of RAM shows up under system properties and DxDiag. However, CPU-Z from CPUID shows 8 slots of memory each with 2 GB (which is indeed what is loaded). Why is there this discrepancy and how can I make the machine use all of it again? Thanks.

 

[Arris]

Has the machine been moved? Even though some software is correctly reporting the memory it would be worthwhile opening it up and checking all the sticks of memory are firmly pushed down and correctly seated in the slots. I'd guess the different software has different methods of querying the system properties. Some might actually query the memory, others might just query what the bios reports which might register the ram details even if it isn't functioning properly.

 

[DelJo63]

First verify that the Mac sees all 16GB

 

[gios]

missing RAM

How do I check that the Mac sees the memory? My machine boots directly into Windows. Win XP reports 8 GB of memory under My Computer > Properties and another program reports only 8 GB as well even though eight x 2GB modules are installed (and have been checked for reseating, fully engaged).

 

[DelJo63]

The Spec sheet (http://www.apple.com/macbookpro/specs.html)
says

* 2.4GHz or 2.53GHz Intel Core i5 processor with 3MB shared L3 cache; 2.66GHz Intel Core i7 processor with 4MB shared L3 cache; or optional 2.8GHz Intel Core i7 processor with 4MB shared L3 cache
* 4GB (two 2GB SO-DIMMs) of 1066MHz DDR3 memory; two SO-DIMM slots support up to 8GB
​

you're wasting time & $$ with the 16gb

 

[gios]

I guess I wasn't clear that this was a desktop Pro.

 

[Arris]

Well Win XP 64bit can apparently support up to 128gb of memory so shouldn't be an OS limitation. Can you confirm that the ram is all securely fitted into the slots?