Knowing nothing about macs I'm not sure but if you're saying you currently have a matched pair in A1 and A2 why are you putting them into C2 and D2 and not C1 and C2 (or D1 and D2) like the existing?

(also, are the new the same speed as the existing, be careful you might get better performance out of the 4x4 new and not using the existing 2x1 if it's going to throttle down)

II would imagine that the slots are paired... hence why you are using A1 & A2 at the moment. You therefore need to fill C1 & C2. Don't hold me to that though (it is a Mac after all)!

There was this video ( that Arthur ) Pm'ed me some time ago

Mac Pro (2008) Memory (High Quality) Installation Video at OtherWorldComputing.com

I wont have enough dosh to get enough ram modules to fill / populate all memory slots so just need to know where they go - yes they are paired as far as I am aware.

I was under the impression that the higher density modules go in the lower numeric slots ie A1, B1, A2, B2 so hence why I was going to put the 4 * 4gb memory modules at the start so A1, A2, B1 and B2 have a 4gb memory module each and then C2 and D2 would be the 1gb memory modules

As is printed on the inside of the door of the Mac Pro, FB-DIMMs must be installed in a particular order as well. The default configuration shipped with a pair of 512 MB FB-DIMMs installed in the first and second slots (towards the "gold fingers" in the top riser card), which leaves six slots free. The next pair of FB-DIMMs must be installed in the first and second slots of the bottom riser card, the next pair in the remaining slots of the top riser card (slots three and four), and finally the last pair in the last two slots (three and four) of the bottom riser card.

How do you upgrade the RAM in the original Mac Pro? How much RAM of what type does it support? @ EveryMac.com

Originally Posted by kmount

How do you upgrade the RAM in the original Mac Pro? How much RAM of what type does it support? @ EveryMac.com

Am sure that was the original mac pro from 2006 or there abouts. I have the 2008 model which came with 1gb in riser card A and 1 gb in riser card b ( total of 2gb )

Also the ram as shown in the link is 667 Mhz, not 800

*shrugs* it says revised in 2009.

I'm just googling.

Did you look on the inside of the case door to see if it provides info on there?

Regardless of the speed I suspect they would have kept to the same conventions if they are still deploying on two riser cards aligned in the same way regardless of the 'size'.

Originally Posted by kmount

Regardless of the speed I suspect they would have kept to the same conventions if they are still deploying on two riser cards aligned in the same way regardless of the 'size'.

Have you ever tried to do any maintenance on a Mac? It wouldn't surprise me if you had to put them in upside-down and point the computer north for it to work

Originally Posted by Ric_

Have you ever tried to do any maintenance on a Mac? It wouldn't surprise me if you had to put them in upside-down and point the computer north for it to work

Fortunately not!

Read the Manual and looked inside the cover and not very descriptive in respect to where to insert different size memory modules although reading about its meant to help if you put the larger memory modules nearer the front so A1, A2 and B1, B2

So I would have filled the First Riser with 2 pairs - presumably one 4gb pair and one 1gb pair and on the bottom riser I would have one pair of 4gb with the last 2 slots empty on Riser B

As a side note I will be getting an anti static wrist strap from flea bay - any suggestions on one and also what am I clipping it to , the mac tower which is made of aluminum or what exactly ?

This is the config I would go with....

Code:

Top Riser
A1: 4GB
A2: 4GB
A3: 1GB
A4: 1GB

Bottom Riser
B1: 4GB
B2: 4GB
B3: ----
B4: ----

According to Intel's documentation for the MCH used in your 2008 Mac Pro (see section 5.3.1), each riser card is treated as a separate "branch". To get the best performance you need to put the highest capacity FB-DIMMs in the first two slots in each riser (A1/A2 and B1/B2) so they are "balanced". At least that is the way I understood it.

The following diagram shows all of the different configurations when using 512MB, 1GB or 2GB FB-DIMMs. Your proposed configuration is closest to #10B, but instead of using 2GB FB-DIMMS you would use 4GB FB-DIMMs.