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Precision 5520/7520 RAM upgrade support (info)
FYI I have the above (7520) and DDR4-3200 (PC4 25600) SO-DIMM does not appear to function (due to BIOS constraint). I would have thought it could negotiate to the supported next-lower speed tier DDR4-2666 (PC4-21300) but it does not. The modules are JEDEC standard genuine SK Hynix modules. When inserted, it does not POST and gives the diagnostic LED indicator for memory configuration error.
However! I discovered that if I insert one DDR4-2666 and DDR4-3200, it will work! I speculate there is a default or 'primary' DIMM slot that BIOS reads SPD first and then perhaps applies it to the other modules (i.e. forcing the others to run at that frequency). With the DDR4-3200 in that slot (or both), it won't configure.
tcsenter_d1db75
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February 4th, 2024 22:30
Yes I forgot to state the capacity: 2 x 8GB SO-DIMM for total of 16GB. The RAM is completely compatible with the Intel memory controller, it would only need the BIOS meminit code to be intelligent enough or 'aware' of DDR4-3200 speed bin and negotiate the lower frequency to DDR4-2666 (or DDR4-2400 for that matter) which is officially supported. This is one of those 'we could, but we're not going to' support issues DELL has decided to impose in it's BIOS/firmware.
I just thought it was interesting that when a 2666 module is installed in the first slot and 3200 in the second, it works. But if you swap them around, it doesn't. And if both are 3200, it doesn't. So there is definitely a primary/default slot that sets the configuration for the channel.
(edited)
JOcean
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February 3rd, 2024 17:51
The specs call for 2400 RAM and 2667 if you are using Non-ECC RAM. I would suspect it is a RAM compatibility problem. With that mix of RAM the system is running at 2666 assuming you are using Non-ECC RAM. With all 3200 RAM the system is not running within specs.
(edited)
tcsenter_d1db75
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April 27th, 2024 00:39
It is a "RAM compatibility problem" in the sense that the BIOS is NOT prepared to recognize DDR4-3200 module and auto-negotiate the memory frequency down to the next supported frequency (as these things are DESIGNED to do). I've proven this by the fact that if a DDR4-2666 module is inserted along with the DDR4-3200, it all works at the DDR4-2666 frequency, but only when populated in a particular order that places the DDR4-2666 module in a particular socket. I don't know how it could have been explained any more clear.
JOcean
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April 27th, 2024 00:42
@tcsenter_d1db75 Thank you for your reply perhaps another user can be of more help.