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TheChicken
Fanfold Paper
Posts: 7
Registered: ‎12-22-2018
Location: CA
Views: 1,483
Message 1 of 15

P52 RAM Frequency

Is there any possible explainations as to why the RAM speed is restricted to 2400 MHz even tho they are designed for 2666MHz, and the fact that i7-8850H does support 2666MHz?

(Yeah Ik that’s what it says in the configuration page and I paid for 2400 MHz, but it would be quite unreasonable since 1) it is a 2666 MHz RAM in there, and 2) there is no option for 2666 MHz RAM configuration.)

Community SeniorMod
Community SeniorMod
Posts: 9,702
Registered: ‎01-01-2010
Location: US
Views: 1,462
Message 2 of 15

Re: P52 RAM Frequency

Looking at the platform specs, it describes 2400 as the speed limit and says it is an Intel limitation.  I was curious and tried to check the  capabilities of the chipset ( CM246).  

 

I found this document:

https://www.intel.co.jp/content/dam/www/public/us/en/documents/datasheets/300-series-chipset-pch-dat...

 

A lot of it is over my head, but way down on page 181 it talks about the I2C bus speed of 2400.  I think that's all you can get.  Memory comes much faster for applications that allow overclocking, but your CPU doesn't allow that process, and the cooling and power supply would also be affected.  


Rich


I do not respond to requests for private, one-on-one help. Your questions should be posted in the appropriate forum where they may help others as well.

If a response answers your question, please mark it as the accepted solution.

I am not an employee or agent of Lenovo.
bobbie424242
802.11n
Posts: 44
Registered: ‎12-20-2018
Location: FR
Views: 1,418
Message 3 of 15

Re: P52 RAM Frequency

I ordered a P72 with 2x8 GB RAM labeled as 2400 Mhz and received it with 2666 Mhz RAM instead. Brand is Samsung.

Lenovo ThinkPad P72 - i7-8850H / 16GB DDR4-2400 / 1TB Samsung 970 Evo / 1TB HDD / 17.3" UHD / Intel UHD 630 / Quadro P600 / 99W Battery / Linux distro: openSUSE Tumbleweed
Community SeniorMod
Community SeniorMod
Posts: 9,702
Registered: ‎01-01-2010
Location: US
Views: 1,398
Message 4 of 15

Re: P52 RAM Frequency

The 2666 ram is certified to run at bus speeds, up to 2666.  In this case, it will run at 2400


Rich


I do not respond to requests for private, one-on-one help. Your questions should be posted in the appropriate forum where they may help others as well.

If a response answers your question, please mark it as the accepted solution.

I am not an employee or agent of Lenovo.
pjg
802.11n
Posts: 192
Registered: ‎05-30-2009
Location: CA
Views: 1,373
Message 5 of 15

Re: P52 RAM Frequency

Regarding this issue, I have a P52 with the Xeon E-2176M processor and 32 GB Samsung DDR4-2666 (PC4-21300) memory.

 

However, when I run HWINFO32 or CPUZ, they both report the clock rate for the memory to be 1200 MHz (12 x 100 MHz).

 

What don't I understand ?

 

HWINFO-Summary.png

Community SeniorMod
Community SeniorMod
Posts: 9,702
Registered: ‎01-01-2010
Location: US
Views: 1,369
Message 6 of 15

Re: P52 RAM Frequency

@pjg I have learned that free software (and some commercial SW) often does a poor job of dealing with new and uncommon kinds of hardware, like your mobile xeon


Rich


I do not respond to requests for private, one-on-one help. Your questions should be posted in the appropriate forum where they may help others as well.

If a response answers your question, please mark it as the accepted solution.

I am not an employee or agent of Lenovo.
Community SeniorMod
Community SeniorMod
Posts: 7,150
Registered: ‎01-13-2008
Location: US
Views: 1,360
Message 7 of 15

Re: P52 RAM Frequency

Is this one of those classic deals where the utility shows actual clock frequency, but since it's DDR (dual data rate) it's actually running at 2x the shown speed?

 

Per the interwebs, that seems to be how HWINFO reports RAM clock rate.

 

Z.


The large print: please read the Community Participation Rules before posting. Include as much information as possible: model, machine type, operating system, and a descriptive subject line. Do not include personal information: serial number, telephone number, email address, etc.


The fine print: I do not work for, nor do I speak for Lenovo. Unsolicited private messages will be ignored - questions and answers belong in the forum so that others may contribute and benefit. ... GeezBlog

 

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pjg
802.11n
Posts: 192
Registered: ‎05-30-2009
Location: CA
Views: 1,352
Message 8 of 15

Re: P52 RAM Frequency

@@. Thanks.  That makes much more sense than the previous answer...

newtonx
Punch Card
Posts: 2
Registered: ‎01-04-2013
Location: CA
Views: 692
Message 9 of 15

Re: P52 RAM Frequency

Hi richk,
If I'm adding ram to my existing P52, should I buy 2400 or 2666?
Thanks!
Morfinas
Token Ring
Posts: 7
Registered: ‎05-30-2019
Location: LT
Views: 659
Message 10 of 15

Re: P52 RAM Frequency

Hi,
I bought a Crucial CT2K8G4SFS8266
Everything works.

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