Precision 7740 memory upgrade

Question

I've recently bought a Precision 7740 with an i9 CPU.
The machine came with 16GB but I want 64GB, so I bought 4x16GB modules that I put in the machine.
However, it will not boot with this memory. If I put back the original memory it works fine.

So, is there a special requirement on the memories?
The modules I bought were
HyperX (i.e. Kingston) HX426S15IB2/16 which is a non-ECC 16GB DDR4 SO-DIMM @2666MHz.

If I look at Kingston's memory configurator, they recommend KCP426SD8/16 modules for a Precision 7740 and those modules are non-ECC 16GB DDR4 SO-DIMM @2666MHz...
The differences are that the HyperX memories are CL15 whereas the others are CL19 & x8, but faster memories normally always work replacing slower memories and memory-ranking (x8) normally doesn't matter.

I'm not particularly fond wasting money and buying more memories but if I must, I will - but in such a case I want to be sure that the new memories will work.
So my question is: What was wrong with the HyperX memories?

JOcean · Answer

The memory should work unless you have a bad RAM module. Have you tried installing them one at a time. In other words try 1 and if it works pull it and try another just to confirm the integrity of each module? If that works then install 2  then pull them and try the other 2. Other than that it can only be incompatibility. Not that it matters but interesting that Crucial does not show 4 x 16 GB as a 64 GB kit. All they show is 2 x 32 GB which should not make a difference but Crucial may have found issues with 4 x 16 GB. That page is here.

DKmn · Answer

I had the same issue with getting generic ram that should have met spec. I then used Crucial's compatibility checker (https://www.crucial.com/usa/en/compatible-upgrade-for/Dell/precision-7740). Got the specific SKU they listed and it was fine.

CRom11 · Answer

Hi,

sorry to revive old thread.

Just received my 7740 and using the crucial website I bought BL2K32G32C16S4B, which is 2x32GB 3200MHz. Laptop doesn't boot so thought it might need BIOS update, run that to the latest 1.8 (something, latest as of writing this post) and no luck.

Any ideas?

Thanks

CenturionX · Answer

Exactly the same problem here with Precision 7540 memory upgrade attempt with Crucial 3200MHz RAM. Doesn't boot. Updated BIOS to 1.9.0. Still doesn't boot. Crucial of no help. Call to Dell support was of no help. 100% compatible according to Crucial website. Seems to be 0% compatible. Have not seen a single mention of success upgrading 7540 or 7740 machines with Crucial (and Kingston for that matter) 3200MHz memory.

CRom11 · Answer

If I'm reading the new Setup and specification for 7740 correctly the restriction of how many 3200MHz modules can be used has been lifted..

Can someone confirm that 4x32GB 3200MHz will work, please? currently running 2x8GB 2666MHz + 2x32GB 3200MHz but looking to get all 4 x32GB 3200MHz

Thanks

catonyx · Answer

I have a very similar question. Can mixed sizes of dimm used to avoid needed to remove the harder to reach primary slots (under the keyboard)? I would rather just add more to the back secondary slots.

DellStA · Answer

Hi All,My 7740 came with 4 * 8GB modules. After I replaced two of them with 2*32GB modules (HyperX, right specs (even faster) but not certified for this notebook) in the secondary memory location (on the back) I had the non booting issue as described here. putting in only one 32 GB module (leaving one slot free) did work (48 GB total memory). After I put the 2 * 32GB modules in the primary memory location (under keyboard) and putted the 2*8GB module in the secondary location, everything worked fine. Now running with 80GB! Hope this helps.

Hugo Dominguez · Answer

Hi, I have the same doubt.I need buy this memory:https://www.amazon.com/HyperX-Impact-3200MHz-Memory-HX432S20IBK2-64/dp/B08492TQGQ/ref=sr_1_5?dchild=1&keywords=ddr4%2Bram%2B64%2B3200mhz%2BSODIMM&qid=1620053804&sr=8-5&th=1 Is it the same one you bought?Thanks.

DellStA · Answer

Hi Hugo, Sorry for the later reply. Yes indeed that is the kit I ordered and still use without any issues. kind regards  Sander

GutenTagHallo · Answer

I know it has been a while, but have you found an answer to your question?

AaronD1993 · Answer

I just had the same problem. Fist I was going to add 2 16gb sticks to slot A and C but the laptop would not start, then I tryed replacing the 2 8gb sticks i had  in the slots B and D but no startup eighter. So i thought the to 16gb sticks were broke. But suddenly the Laptop would not even start when the 2 8gb sticks were back in their original slots B and D what left me wondering. I could finally get it to work by pressing 'windows' 'shift' and 'b' multiple times in a row, while the black screen was showing and the power led was glowing, the first time. after I had tryed to change the ram the laptop would not turn on properly, instead it would only show a black screen and the power button aswell as caps were lit. But i had not installed all ram sticks (i thought some were broke) when i managed to 'activate' it again. So i gave it one last try with all sticks installed. The screen was black at first again and the key kombination did not seem to work so i just went wild on all of the keyboard buttons and after sliding through the F-row it aktivated again .. I do not know what did the trick but for sure not pressing any button left the screen black befor over minutes. I tryed this because i had to reactivate my tablet that way the other day, it also suddenly would not turn back on, and by coincidance it worked here too. Hope that helps someone else too

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Precision 7740 memory upgrade

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