Dell Precision 7740 with i9-9980HK running RAM at 3200?

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cyclone3d

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So I was going through my stash of RAM and found a couple Dell 32GB DDR4-3200 SODIMM modules I had forgotten about.

Decided to try them in my Precision 7740 sporting the i9-9980HK CPU to see if they would run properly.

I already had 4X 16GB DDR4-2933 sticks running in this laptop at 2933.

Once I installed the 32GB sticks, it dropped the RAM speed down to 2666, which reminded me that that is why I wasn't using them before.

After looking online, I found a post on the Dell forums that said to use one brand in slots A,B and the other brand in C,D. (For a Precision 7550)

This initially resulted in a NO POST, so I swapped out the ADATA 16GB 2933 sticks for Crucial 16GB 3200 sticks.

It then posted and is running the RAM at 3200 despite the official specs being 2666.

Running the onboard diagnostics now and expect it to work just fine.

Was not able to find another instance of anybody doing this so figured it might be of some interest.
 
Well, that POSTs but locks up in diags and the system gets way hotter than normal. Bummer.

The ADATA sticks are the only kind I have in 2933 and they are not playing nice with the 3200 sticks as they clock down to 2666 instead of running at 2933.
 
Larger ram sticks are hard to run at their full speed in systems, you are very dependant on your cpus memory controller. Sounds like your cpu is just unable to handle those 32 GB sticks at full speed, or with the extra old sticks. You may want to see if there is a bios update, as those can help with memory stability...but you may just be unable to run those sticks well.
 
Starfalcon said:
Larger ram sticks are hard to run at their full speed in systems, you are very dependant on your cpus memory controller. Sounds like your cpu is just unable to handle those 32 GB sticks at full speed, or with the extra old sticks. You may want to see if there is a bios update, as those can help with memory stability...but you may just be unable to run those sticks well.
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Yeah, my guess is it is the IMC as well as the BIOS not limiting the RAM speed correctly.

I could try these combos at 3200 in the 7740...
2x 8GB
2x 16GB
2x 8GB + 2x 16GB
4x 16GB.

The newer 7550 limits the RAM speed to 2933 which is what the 10th gen Intel CPUs officially support.

Definitely a bug in the 7740 BIOS, and it has the latest available BIOS installed.
 
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