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52959
March 14th, 2012 12:00
R510 - memory upgrade options
Hi, I am struggling to understand all the options I have when adding memory to our R510 server. It is dual processor. I understand the layout of 3 channels per processor with slots A-1 and A-4 making up a single channel. Where I'm having trouble with is if memory of different sizes can be mixed. The statement in the manual that is throwing me off is this:
"Memory modules of different sizes can be mixed in A1-A4 or B1-B4 (for example, 2-GB and 4-GB), but all populated channels must have identical configurations."
When I had first read this I understood 'A1-A4' as meaning all of the slots, A1, A2, A3, A4. I think it means only A-1 and A-4 though since they are two slots making up a single channel. If it is just referring to A-1 and A-4, it still doesn't quite make sense to me because how would you ever mix sizes in these two slots and have them equal the size in slots 2 or 3? Meaning, if I had a 2 GB and 4 GB DIMM in 1 and 4, that channel is 6 total. If I understand "all populated channels must have identical configurations" to mean the same amount of RAM in GBs, it would mean slots 2 and 3 would need 6 GBs each. Unless "all populated channels must have identical configurations" means the channels that correspond to each other on both procs?
If someone can explain to me what I'm missing and give an example of how you could mix RAM sizes (assuming all the same speed and all dual ranked), that would be great.
Thanks!
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pwhX2
6 Posts
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March 16th, 2012 10:00
Yeah the corresonding slots between A and B always match. If I put just the DIMMs of a particular size in (so either all the 8GBs only, or all the 2 GBs only), things work fine. It's only when I mix them within a bank (while still matching between A and B), that the machine won't even POST. I'll put it to bed for now, I'm glad to hear I understand the docs right, I'll just have to be super careful when buying my next upgrade. Thanks for you thelp.
theflash1932
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16.3K Posts
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March 14th, 2012 12:00
Because there are so many combinations, can you tell us what you are hoping to upgrade to? What is your goal?
pwhX2
6 Posts
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March 14th, 2012 13:00
We inherited a server with (4) 4 GB DIMMs. I need to upgrade memory and would like to buy a couple 16 GB DIMMs, but not sacrifice the use of the 4 GBs. So my first thought was you could put a 16 GB on each side in the same slot, and then the same with the 4 GBs, but I have seen references that this does not work. For me it all comes down to clarification of the statement I referended from the manual. Can different channels have different size RAM chips and how does this relate to the 2-slot channel 1.
Thanks.
theflash1932
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16.3K Posts
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March 14th, 2012 16:00
Each processor has a bank of memory slots. They are numbered 4,1,2,3 (starting with the black-tabbed slot closest to the processor). Each processor must have a memory configuration that exactly matches the other processor. Each has three memory channels: channel 0 = slots 1 and 4, channel 1 = slot 2, channel 2 = slot 3. Each bank must be populated starting with slot 1. Different size DIMM's can be used in slots 1-4, BUT what you do to one processor bank, you must do to the other.
Example 1:
You have processor 1's configuration as follows:
4GB in slot A1
2GB in slot A2
1GB in slot A3
slot A4 empty
So, processor 2's configuration should be as follows:
4GB in slot B1
2GB in slot B2
1GB in slot B3
slot B4 empty
Example 2:
You have processor 1's configuration as follows:
8GB in slot A1
2GB in slot A2
2GB in slot A3
slot A4 empty
So, processor 2's configuration should be as follows:
8GB in slot B1
2GB in slot B2
2GB in slot B3
slot B4 empty
Example 3:
You have processor 1's configuration as follows:
16GB in slot A1
4GB in slot A2
4GB in slot A3
slot A4 empty
So, processor 2's configuration should be as follows:
16GB in slot B1
4GB in slot B2
4GB in slot B3
slot B4 empty
The important thing is that the memory configuration of processor 1 matches that of processor 2.
theflash1932
11 Legend
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16.3K Posts
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March 14th, 2012 16:00
Channel 0 can only have two DIMM's if all slots are populated.
pwhX2
6 Posts
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March 16th, 2012 08:00
Hi, I posted a response the other day but it looks like it didn't save or something. I knew that each proc needs the same config, i just speak in terms of one side for the sake of discussion. My main question comes around mixing different size DIMMs on the same processor bank. I have obtained some additional DIMMs but cannot get things to work. Can you let me know any reason why the below configs would not work? All DIMMs are dual ranked. I reference A, but the B side is the same in my tests. Thank you.
8GB in slot A1
8GB in slot A2
2GB in slot A3
slot A4 empty
8GB in slot A1
8GB in slot A2
2GB in slot A3
2GB in slot A4
theflash1932
11 Legend
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16.3K Posts
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March 16th, 2012 09:00
"I reference A, but the B side is the same in my tests." Not exactly sure what you mean by that, as your list doesn't match up ... assuming you actually meant to identify the A and B slots, going off of the configuration you listed:
8GB in slot A1
8GB in slot A2
2GB in slot A3
slot A4 empty
8GB in slot B1
8GB in slot B2
2GB in slot B3
2GB in slot B4
Either A4 must be occupied or B4 must not be occupied.
If I were to assume you meant to write the following:
8GB in slot A1
8GB in slot A2
2GB in slot A3
slot A4 empty
8GB in slot B1
8GB in slot B2
2GB in slot B3
slot B4 empty
Then I don't see any reason, from what is written in the documentation, why it would not work ... assuming, of course, that all memory conforms to the required specifications like speed (PC2-10600), type (RDIMM/UDIMM), and layout (x4,x8). For example, if the 8GB stick in slot A1 was 2Rx4 and the 8GB stick in slot B1 was 2Rx8, then these would not match and you would receive an error/warning; likewise, if slot Ax was 1333MHz and slot Bx was 1066MHz (or even 1333MHz at 10666 vs. 10600 might be enough of a difference), then these would not match and you would get an error/warning.
pwhX2
6 Posts
0
March 16th, 2012 10:00
Thanks, there must be some difference you mentioned that I'm not seeing. I'm just glad to get confirmation that I was understanding the documentation right, and that different sized modules can be used. To clarify my post, I did type what I meant. I have two examples, 1 with 3 slots occupied and 1 with 4 slots occupied. As I said in the post I was not listing out the "B" bank, as I understand it needs to match "A" and it always has in all my tests. I gave two examples of configurations I'd tried, with both and A and B populated as such.
theflash1932
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16.3K Posts
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March 16th, 2012 10:00
Ok, I see what you're saying ... I didn't realize they were two different configuration attempts. The first one I see no issue with at all. The second one sounds like it should work ... the only thing I wonder about is the differing DIMM sizes for both DIMM's on channel 0 (8GB and 2GB), although the documentation doesn't make that specific distinction when saying that sizes can be mixed in slots x1-x4. Are all of "matched" DIMM's identical, as I described above (no variance at all)?