Pro memory config please

[sspeed]

Hi Everyone..
I am new to this forum and pretty new to Macs generally.
However I am lucky enough to own a 2009 Mac Pro which has 8GB of memory (2 x 4gb)..
I have aquired another 8GB of memory but it is 4 x 2GB sticks.
I hear that the Mac Pro is very particular about how memory is installed.
Please can you advise how I install with maximum performance in mind.
Thanks in advance for any help you can offer,

Simon

 

[gugucom]

Best performance for a MacPro4,1 octad requires six identical DIMMs. This is because each CPU has three channels which should be filled with the same amount of compatible memory.

Assuming that your 4 and 2 GB DIMMs are both of UDIMM type (unbuffered) you could buy two more 4 GB DIMMs. An optimal configuration would be:

Slot Size

1.......4
2.......4
3.......2
4.......2

5......4
6......4
7......2
8......2

In this case each channel would be filled with 4 GB because slot 2 and 4 serve the third channel and slots 7 and 8 serve the sixths channel. There may be minimal bandwidth losses compared to six identical DIMMs but it is not worth consideration under the real world conditions of your system.

 

[sspeed]

Thank you

Thank you very much for such a quick response..
I shall order 2 x 4GB sticks of memory..
Have you any suggestions where to buy from?
Thanks in advance

 

[gugucom]

http://www.crucial.com/uk/store/mpartspecs.aspx?mtbpoid=70357C5FA5CA7304

Assuming you have unbuffered memory the above should fit. But you pay premium for a UK supplier.

http://cgi.ebay.de/Hynix-1x-4GB-Mac...itsspeicher?hash=item518d064d57#ht_2889wt_991

This is a better price in Europe

 

[sspeed]

Excellent

Once again, thank you.
There is indeed quite a price difference.