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T7820 & T5820 Load Reduced (LR) Dimms, do they actually work on either platform?
T7820 & T5820, can you use LR Dimms on either platform?
Please don't just quote the Dell compatibility list as we all know that's only the DIMMS that Dell either sell themselves or have physically tested themselves, so that's a whitelist and not a blacklist.
I'm trying to find out if others have actually tried LR DIMMS in either system and what the results ended up being.
I have read, but can't find it now, that the T7820 doesn't support LR DIMMS, but not sure if it was an authoritative source.
Why am I asking? I've come across some 32GB LR DIMMS that I could use as they would be perfect to make a virtualisation server, if they'll work then juggle around the spared up 'normal' DIMMS to use in other units, but both my T5820 and T7820 are in hard to get places and are production boxes, so not terribly easy to pull them out just to test this theory.
pduk
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March 25th, 2023 07:00
Sorry, just to add, I'm aware that both user manuals only refer to RDIMM units, but many a time I've seen a user manual say one thing that has turned out not to be fully correct.
JOcean
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March 25th, 2023 08:00
After hunting around the only reference I could find that would seem to answer the question is from Crucial. They do not list any LRDIMMS as compatible with the 7820 but they do list LRDIMMS that are compatible with the 7920. That would lead me to believe that they are not compatible with the 7820. I know that this is not the rock solid answer you are looking for but it's the only source I could find with any reference to LRDIMMS and the 7820.
pduk
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March 25th, 2023 09:00
Unfortunately I can't use these LRDimms in my 7920 units as the Dimms are 2133 and the processors are Gold 6132 units so won't support such slow memory.
Thus the pursuit of a juggling exercise, I have 512Gb of this LRDimm memory, so would like to try to find a way to use it, even if it's just to build a virtualisation server for non CPU bound tasks.
pduk
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March 25th, 2023 09:00
Thanks for the reply, it's interesting as the Dell manual for the T7810 for example only states that RDIMM units are compatible, however in the same manual they also state that you can't mix RDIMM and LRDIMM units and Crucial again list no LRDIMM units compatible with the 7810.
https://uk.crucial.com/compatible-upgrade-for/dell/precision-7810#memory
https://dl.dell.com/topicspdf/precision-t7810-workstation_owners-manual_en-us.pdf
Page 36 additional information, note, paraphrased "...cannot mix DIMM and LRDIMM units..."
Page 53 Memory Type 2133 DDR4 RDIMM ECC
I realise some reading this may think I'm being picky, but I've been around the IT business long enough to know that the 'official' documentation is more often not as comprehensive as many might think and the only 'real' proof is trying it yourself, or reading the first person experience of others who have tried it.