2008 Mac Pro 6 memory module performance

[mac_shinobi]

Looking here :

 

diglloyd - The Apple Mac Pro - All About Mac Pro Memory

 

About half way down the page here :

 

Memory performance—8 modules vs 4

 

AnandTech has an interesting article “Understanding FB DIMMS”, as part of its discussion of the new Apple Mac Pro (FB-DIMMS are the technical name for the type of memory module used by the Mac Pro).

The claim is that filling all 8 memory slots will in theory reduce memory performance over using just 4 slots due to the nature of the serial data transfer in an FB-DIMM—increased latency of 3-5 nanoseconds. No measurable difference in memory copy speed was observed with memory in slots 3 and 4 as compared with slots 1 and 2. That doesn’t mean there isn’t a difference in some real world applications, because bandwidth and latency are independent factors.

 

I want to assuming I don't get too much of a performance hit use 6 modules

 

4 * 4gb and the stock 2 * 1gb modules

 

Will this slow it down or would I be better just using the 4 * 4gb and leaving the 2 * 1 gb modules out ?

[mac_shinobi]

bump , anyone ?

[Arthur]

...

 

http://www.barefeats.com/harper3.html

http://eshop.macsales.com/Reviews/Framework.cfm?page=/Benchmarks/macproearly08ram/article.html

[mac_shinobi]

So basically saying use the 16gb ( 4 * 4gb modules ) and leave the stock RAM out of the machine or put them in ?

 

As per the articles it states that the 1gb modules tend to be single rank - i still dont have a clue how id tell as I cant see much info on the ram sticks ?

 

Ive ordered the 16gb ( 4 * 4gb ) which I should get by the end of next week. Obviously just trying to get confirmation on if I should install it as per the 10B Diagram you posted which was one pair of 4gb on riser A and one pair of 4gb on riser B. Then the Stock RAM in Riser A in slots 3 and 4 and slots 3 and 4 on riser b were empty.

 

Or do I go with one pair of each on risers A and B and leave slots 3 and 4 on both cards empty ?

 

Plus I can't see any setup that shows a similar config to the one I am going to get using either 4 or 6 slots using 4gb modules and 1gb modules

Edited April 27, 2011 by mac_shinobi