Multiple RAM brands Mac Pro 2012

Question

rohan3au Author

Level 1

5 points

Multiple RAM brands Mac Pro 2012

Hey Guys,

A little help wpould be awesome!

Ok, so I ordered my Mac Pro 2012 with 6GB of RAM and I bought my own to put in to save heaps of cash.

It came with 3x 2GB sticks of this:

http://www.memory4less.com/m4l_itemdetail.aspx?itemid=1462334430

And I put in 2 sticks of kingston 8GB:

http://www.ec.kingston.com/ecom/configurator_new/partsinfo.asp?ktcpartno=KVR13R9 D4/8I

The computer wouldn't turn on (power light flashed) when I had 2 sticks of the apple RAM and my 2 sticks.

I took out the apple sticks and left my 2 sticks in and it booted fine.

Basically, i want to order 2 more sticks of 16GB OWC ram:

http://www.macfixit.com.au/apple-memory-ram/apple-mac-pro-ram-memory/mac-pro-mid -2010-memory-ram/mac-pro-mid-2010-6-core-memory-ram/16-0gb-1-x-16-0gb-owc-pc1060 0-ddr3-1333mhz-ecc-fb-dimm-240-pin-ram.html

Will I face the same issue of my mac not booting up with the OWC and kingston ram both installed?

Thanks!

Mac Pro, OS X Mountain Lion (10.8.4), Mid-2012 Mac Pro

Posted on Aug 20, 2013 4:43 AM

Reply

Answer 1

kaz-k

Level 8

49,068 points

Aug 20, 2013 6:36 AM in response to rohan3au

I've been using Micron and Elpida Memory sticks together and they work with no trouble.

Reply

Answer 2

The hatter

Level 9

60,990 points

Aug 20, 2013 7:32 AM in response to rohan3au

Some 8GB DIMMs do not work with others. Has to do with ranking and type of DDR3 ECC - I should bookmark a good explanation that I have seen here and on MacRumors and likely others would have.

OWC will give you something for your Apple memory.

Difference between RDIMM and UDIMM

R = Registered, U = Unregistered, FB = Fully Buffered, 5520 always needs ECC registered fully buffered.

please strictly stick to the memory compatibility list for your motherboard - there are even more differences than buffered vs. unbuffered (eg. single/dual/quad rank) - when purchasing memory not on the compatibility list get a written confirmation from the dealer the modules will work for a certain motherboard.

When you populate slots 3 & 4 you do take a hit as they share one channel.

If 2 memory DIMMs are used per channel, this "...results in a reduction of maximum memory bandwidth for 2DPC (DIMMs per channel) configurations with UDIMM by some 5% in comparison to RDIMM." ^[1] (p. 14). This is because "...when you go to 2 DIMMs per memory channel, due to the high electrical loading on the address and control lines, the memory controller uses something called a “2T” or “2N” timing for UDIMMs. Consequently every command that normally takes a single clock cycle is stretched to two clock cycles to allow for settling time. Therefore, for two or more DIMMs per channel, RDIMMs will have lower latency and better bandwidth than UDIMMs." ^{[2] http://en.wikipedia.org/wiki/Unbuffered_memory}

How To Install and Remove Memory Mac Pro

https://support.apple.com/kb/HT4433

Reply