Mixing 8500E and 8500R memory

Question

Mixing 8500E and 8500R memory

Hey all, new to the Mac Pro game...

Just bought an 8 core Early 2009 Mac Pro Tower! got it for a crazy amazing deal...

so any way... I have the following issue.

My system came with 8GB 4 x 2Gb memory

they are as follows

Hynix 2GB 2Rx8 PC3-8500E-7-10-E0

they all work fine

So I purchased the following to add an aditional 8GB

Samsung 2 x 4GB 2Rx4 PC3-8500R-07-10-E1-D2

They also work just fine

BUT here is where I have a problem, If i put say the 4 GB in slot 1 and 4 then the others in slost 2,3,5,6 system wont boot just get a blinking light

tried every combo I can think of... anyone know why or can point me in the right direction?

Also can i use the 1333 mhz ECC memroy as I have a line on 32gb for a good price.. I asume it will just downclock... I am used to PC's very new to Mac Pros

Thanks for any help

Mac Pro, OS X Mavericks (10.9.3)

Posted on Jun 6, 2014 9:42 PM

Reply

Answer 1

Jun 6, 2014 10:01 PM in response to nathanielfromcalgary

The blinking power light says, "Not enough working RAM to start up".

If the R stands for Registered (they have a buffer register on the output) that kind does not play nice with any other kinds.

So you always try each kind by itself to see what seems to be working first. (which it appears you did.)

So the new ones may NEVER work with the old ones.

Some kinds of memory do NOT clock down happily when you try to run them at slower speeds -- they simply don't work. So do not assume they will all clock down.

--------

Macs are very, very fussy about memory. so the best advice is to buy from a Vendor who knows Macs, and you tell the Vendor your Model, and they send you RAM guaranteed to work:

"It works in your Mac,

or your money Back."

--------

In the 2009 and later models of Silver Tower, the first three sockets on each side are independent, and can be filled by the each. Matched triples offers slightly better speeds than other combinations, but not by much. Slots 3 and 4 on each side are shared, so adding a DIMM there gives a miniscule slowdown. Having enough memory to do your work will more than compensate for any slowdown.

Reply