Max RAM is 16 G;  system will take 2.5" SSD or an M.2 2280 SSD.

https://www.crucial.com/compatible-upgrade-for/dell/latitude-e7470

Wrong.

The correct answer would be 32GB.

Max. memory = 32GB

Dual Channel or as Dell calls it "Dual Interleave"

Best regards,

U2

why a lot of people said that maximum RAM is 16 GB, and which is the true compatible speed, 2133 or 2400 mhz ?

Welcome to the Dell Community @masriadimappa 

To answer your questions!!!

" Why a lot of people said that maximum RAM is 16 GB "

Because they only go by what they Google or see in the manuals.

https://www.dell.com/support/manuals/en-us/latitude-e7470-ultrabook/late_e7470_om/specifications?guid=guid-5a37743b-091b-4716-9574-f99f29e7bf1c&lang=en-us

Manuals in no way reflect the limitation of the hardware.

That is why it try to test as much as I can before I post.

"Is the true compatible speed, 2133 or 2400 mhz ?"

As far as RAM speed goes 2400MHz will work but it will clock down to the CPU memory bus speed.  "2133MHz"

Best regards,

U2

so here are my optyions

- 16 GB Ram (2x8) 2400 mhz

- 16 GB Ram (1x16) 2400 mhz

- 32 GB Ram (2x16) 2400 Mhz

- 16 GB Ram (2x8) 2133 mhz

- 16 GB Ram (1x16) 2133 mhz

- 32 GB Ram (2x16) 2133 Mhz

my laptop is Dell Latitude e7470 non touch screen

which is the best will i take ?

I think you need to try; I did upgrade my old E7470, Dell said it is 16GB Max, Intel said 32GB max, I went with 2x32GB worked like a charm, but whatever speed you take, you will get 2133MHz only, since no XMPP support.

Welcome to the Dell Community @macrae 

Thanks for posting that you have successfully upgraded to 64GB max on an E7470.

People have posted at times that they were able to exceed the max memory specifications of a CPU.

At the time of my test I had no 32GB to test 2x32GB for a total of 64GB.

I still have no 32GB DDR4 SIMM's. "Yet"

Could you please post a pic of the BIOS like the one in my post???

Best regards,

U2

NOTE:

Memory speed is a result of the CPU and Chipset limitations.

Thank you @U2CAMEB4ME ,

Here is my BIOS picture:

Thanks for the pic @macrae 

Did you ran any resource monitor app to check the memory usage above the CPU limit of 32GB???

I have hundreds of E7470's but no 32GB DDR4 SIMM's.

When I receive some 32GB SIMM's I'd like to duplicate your tests.

Best regards,

U2

My daughter did rendering 4K short movie couple months back, it crunched till 52GB RAM Usage.

Nowadays mostly used with docker, overall usage around 30-40GB in total