Having RAM in this order, is it slower?

[MythicFrost]

Hey, I've got 18GB of RAM in my MP, I thought I read something about it being faster if you put them in a certain order, or use all the same modules.
So I'm wondering if anyone knows if this order/or these modules will be slower than say, some other order, or if they were all 4GB modules:

• DIMM A/DIMM 1 1GB
• DIMM A/DIMM 2 1GB
• DIMM A/DIMM 3 2GB
• DIMM A/DIMM 4 2GB
• DIMM B/DIMM 1 2GB
• DIMM B/DIMM 2 2GB
• DIMM B/DIMM 3 4GB
• DIMM B/DIMM 4 4GB

Kind Regards

 

[Tesselator]

Hey, I've got 18GB of RAM in my MP, I thought I read something about it being faster if you put them in a certain order, or use all the same modules.
So I'm wondering if anyone knows if this order/or these modules will be slower than say, some other order, or if they were all 4GB modules:

• DIMM A/DIMM 1 1GB
• DIMM A/DIMM 2 1GB
• DIMM A/DIMM 3 2GB
• DIMM A/DIMM 4 2GB
• DIMM B/DIMM 1 2GB
• DIMM B/DIMM 2 2GB
• DIMM B/DIMM 3 4GB
• DIMM B/DIMM 4 4GB

Kind Regards

Yes, there will be some differences, including to do with speed. Use this chart to get it right:

 

[MythicFrost]

Thanks.

If I have 18GB, does 9A apply? I do 4x2GB on the right, and 2x4GB at the top two, and then 2x1GB at the bottom 2?

Kind Regards

 

[gugucom]

Your best bet would be:

• DIMM A/DIMM 1 4GB
• DIMM A/DIMM 2 4GB
• DIMM A/DIMM 3 empty
• DIMM A/DIMM 4 empty
• DIMM B/DIMM 1 2GB
• DIMM B/DIMM 2 2GB
• DIMM B/DIMM 3 2GB
• DIMM B/DIMM 4 2GB

You will provide the fastest access to your memory by that way. It will exceed the effect of having 2 GB more RAM. If you really need the 2 GB:

• DIMM A/DIMM 1 4GB
• DIMM A/DIMM 2 4GB
• DIMM A/DIMM 3 1GB
• DIMM A/DIMM 4 1GB
• DIMM B/DIMM 1 2GB
• DIMM B/DIMM 2 2GB
• DIMM B/DIMM 3 2GB
• DIMM B/DIMM 4 2GB

Would be better. If you want to upgrade buy 2 more 4GB sticks and fit them like this:

• DIMM A/DIMM 1 4GB
• DIMM A/DIMM 2 4GB
• DIMM A/DIMM 3 2GB
• DIMM A/DIMM 4 2GB
• DIMM B/DIMM 1 4GB
• DIMM B/DIMM 2 4GB
• DIMM B/DIMM 3 2GB
• DIMM B/DIMM 4 2GB

 

[Tesselator]

Thanks.

If I have 18GB, does 9A apply? I do 4x2GB on the right, and 2x4GB at the top two, and then 2x1GB at the bottom 2?

Kind Regards

Yeah, just use the logic of the graph to figure out where the 4GB modules go.

9A looks right for that.

 

[ungraphic]

Hmm, good thread. Here's my setup. Someone tell me if its proper;

• DIMM A/DIMM 1 2GB
• DIMM A/DIMM 2 2GB
• DIMM A/DIMM 3 512mb
• DIMM A/DIMM 4 512mb
• DIMM B/DIMM 1 512mb
• DIMM B/DIMM 2 512mb
• DIMM B/DIMM 3 empty
• DIMM B/DIMM 4 empty

 

[Genghis Khan]

Hmm, good thread. Here's my setup. Someone tell me if its proper;
DIMM A/DIMM 1 2GB
DIMM A/DIMM 2 2GB
DIMM A/DIMM 3 512mb
DIMM A/DIMM 4 512mb
DIMM B/DIMM 1 512mb
DIMM B/DIMM 2 512mb
DIMM B/DIMM 3 empty
DIMM B/DIMM 4 empty

Yep, That's right.

Basically, install in matching pairs (with both riser cards mirrored if possible), and the biggest chips on the inner slots.

 

[MythicFrost]

Would this be better for me Riser A 4/2/2/1, Riser B 4/2/2/1 compared to what I currently have Riser A, 2/2/1/1, Riser B 2/2/4/4.

Kind Regards

 

[Umbongo]

Hmm, good thread. Here's my setup. Someone tell me if its proper;

• DIMM A/DIMM 1 2GB
• DIMM A/DIMM 2 2GB
• DIMM A/DIMM 3 512mb
• DIMM A/DIMM 4 512mb
• DIMM B/DIMM 1 512mb
• DIMM B/DIMM 2 512mb
• DIMM B/DIMM 3 empty
• DIMM B/DIMM 4 empty

512mb modules slow down the Mac Pro due to being single rank and the smaller capcaity also affects the speed. I understand it may not be viable to change them out for something else though. Use 6c from the chart for optimum performance.

Would this be better for me Riser A 4/2/2/1, Riser B 4/2/2/1 compared to what I currently have Riser A, 2/2/1/1, Riser B 2/2/4/4.

Kind Regards

That's not a correct setup as slots 1&2 and 3&4 need to match. Either a:4/4/1/1 b:2/2/2/2 for capacity or a:4/4/-/- b:2/2/2/2 for speed. You may not notice a speed increase with what you are doing, but it will be faster.

 

[gugucom]

umbongo just confirmed my earlier post

 

[ungraphic]

512mb modules slow down the Mac Pro due to being single rank and the smaller capcaity also affects the speed. I understand it may not be viable to change them out for something else though. Use 6c from the chart for optimum performance.

Awesome! Thank you!!