Grant Bennet-Alder Apr 10, 2013 7:19 PM in response to mopahhh Level 9 Level 9 (64,592 points) expertise.desktopsDesktopshttps://discussions.apple.com/thread/49 ... 0&tstart=0
Apr 10, 2013 7:19 PM in response to mopahhh
Unlike older Mac Pros that required matched pairs, the 2009 and later models of Mac Pro 65lb tower have four slots on each side (each processor module), and they operate somewhat independently. The first three slots are independent, the fourth slot is shared with the third slot.
1) If you install one module on each side, it will run slower because it cannot interleave.
2) If you install two on each side, it will run about five percent slower than optimum. This does not make a measurable difference.
3) Three modules on each side runs at the fastest memory speed.
4) Four modules on each side runs five to ten percent slower, because slots three and four are shared. In some cases, it may run one step down from its fastest speed. The slowdown is memory speed is usually more than compensated by faster overall operation from having adequate memory.
That being said, in the real world – as with the 2009-2012 model Mac Pros which supported up to triple-channel addressing and even with the 2006-2008 models that REQUIRED matched pairs – more memory trumps multi-channel addressing where you have an application or applications running that make use of that memory.https://blog.macsales.com/22745-mix-and ... -mac-pro-2
Dual-processor computers have eight memory slots, four per processor. You can install 1 GB, 2 GB, or 4 GB DIMMs. Each processor’s memory controller has three memory channels. DIMM slots 1, 2, 5, and 6 have their own channels; slots 3 and 4 share a channel and slots 7 and 8 share a channel. For optimal memory bandwidth, all six memory channels should be used, and memory should be balanced across the six channels. Note: Populating slot 4 or 8 slightly drops maximum memory bandwidth, but depending on the applications used, overall system performance may benefit from the larger amount of memory.https://apple.stackexchange.com/questio ... m-slots-in
If you have Fill in these slots
Two DIMMs 1 and 2
Three DIMMs 1, 2, and 3
Four DIMMs 1, 2, and 5, 6
Six DIMMs 1, 2, 3 and 5, 6, 7
Eight DIMMs 1, 2, 3, 4 and 5, 6, 7, 8
Not your model Mac Pro, but I found it interesting that OWC's RAM was cheaper AND faster!https://www.tekrevue.com/2013-mac-pro-ram-upgrade/
Mac Pro 3,1s needed paired RAM...http://www.everymac.com/systems/apple/m ... emory.html