Optimize RAM frequency for ZBook 17 g5

[Dijkie_82]

Hi,

I have a "HP ZBook 17 G5 Mobile Workstation" and I replaced the ram with 2 exactly the same modules of 16gb 3200Mhz (so faster then specs).

Now they are in slots 1 (backside) and 4 (easily accessible one). I get dual channel support, but only at 2400Mhz.

What slots should I use to get optimal performance, so the max of 2666Mhz? Should i change some bios setting?

This image should give all the info:

Thanks in advance

[banhien]

@Dijkie_82 

Its specs

            https://support.hp.com/au-en/document/c06002455#AbT6

which supports

• 64 GB DDR4-2667 (ECC or non-ECC SDRAM)
• (4) SODIMM slots supporting dual-channel memory (two SODIMMS slots are customer accessible or upgradeable)
• 4 GB, 8 GB, and 16 GB SODIMMs (for Intel Core)
• 8 GB and 16 GB ECC SODIMMs (for Intel Xeon)

You can install higher speed RAM but machine will run at 2666MHz and no option for you to overclock RAM.

Regards.

[Dijkie_82]

Hi BH,

Thanks for your reply. I am still not sure how to read that doc, does it mean that i have to install ram in all 4 slots to get the optimum speed? As you can see in my screenshots, it operates on 2400Mhz, not 2666Mhz. So what am i seeing wrong?

[Huffer]

Here is the Service Manual:

Manual 

A couple noteworthy things. 1. See p. 2. 3 or 4 modules can only work on Quad Core systems. 2. See p. 30. Lists memory as DDR4-2400 but specifies DDR4-2666 as the installed parts. While the word bridge or downclock is not mentioned, I think that is what's happening. Do you have Dual or Quad i7? What exact DDR4-3200 did you install? If its "performance" or "gaming" memory you can expect some compatibility issues with HP notebooks. However, if it runs in dual channel that usually means its working to its best capability. 

[Dijkie_82]

https://www.crucial.com/memory/ddr4/ct2k16g4sfra32a

Maybe the folloowing is more helpfull. It is a 6 core

[Huffer]

I can see you are not using performace type memory, its standard oem Crucial stuff.  I would not have tried to use DDR4-3200 but theoretically it should work to downclock to -2666. Have you ever seen the system run memory at faster than -2400?

[Dijkie_82]

No because the modules it had before were just 2400. Can it have something to do with the slots used? Which should i use in theory? I've replaced it on the backside, but its quite a hassle to take it apart just to try which config is best

[Huffer]

Page 50:

"Primary and expansion memory is installed in a side-by-side conƭiguration in the bottom of the
computer.
If only one memory module is installed, it must be installed in the socket labeled ‘1"

As I tried to say, if you install it in the wrong slots you will not get dual channel. You have dual channel. Appears you have it in Slots 3 and 4. I think you should always use Slot 1 as it says a single module must go there. Generally you would install in odd numbered slots so 1 and 3 is how I would have done it, but I really honestly do not think it has anything to do with where the modules are installed. I think you are seeing a system which runs its memory at -2400 speed. 

[Dijkie_82]

How i installed it was in slots numbered 1 and 3 (on the motherboard), but then i got single channel 2400, so now its in 1 and 4 and i got dual channel 2400. 

Anyways, thanks for your time, soon i will do the operation on the patient and inform you on the outcome.

Otherwise i will have to live with the knowledge i was unable to squeeze the last drop of performance out of it.

[Dijkie_82]

I just realised that the green image has confusing slot identifying numbers, so let ignore those. I was talking in the numbers written on the mb itself. One is in slot 1 and 2 is empty (these are the hard to reach ones under the shield). First i tried the second one in slot 3 then it gave single channel. Now its in 4 and gives dual. 

I read gaming pc's sometimes advice to use 2 and 4 because they are closest to the cpu, but i understand from the docs the should be in 1 + 2