The first, i got some problems with my acer nitro 5 AN515-57, i presented in this question below (in this post, i type wrong AN515-57 to ANA515-57, so sorry).
https://community.acer.com/en/discussion/649001/problem-with-acer-nitro-5-ram-cannot-run-at-3200mhz/p1?new=1And so, i found something wrong on i5-11400H with RAM speed.
In this userbenchmark rankings:
https://www.userbenchmark.com/System/Acer-Nitro-AN515-57/238169#Benchmarks , almost laptop run with i5-11400H has speed of RAM:
10-13GB/s for single channel DDR4-3200MHZ of RAM, show in these screenshots below:



20-23GB/s for dual channel DDR4-3200MHZ, show in these screenshots below:



I know has some cases, dual channel DDR4-3200MHZ got 30-40GB/s, single channel DDR4-3200MHZ got 15-20GB/s. But it's very rare. Almost the case has the result like above.
I noticed a few things wrong here. With single channel DDR4-3200MHZ, speed of RAM is approximately 15GB/s or over, you can see that here:
https://ram.userbenchmark.com/SpeedTest/1203799/Micron-4ATF1G64HZ-3G2E1-1x8GB And with dual channel DDR4-3200MHZ, spped of RAM is approximately 35GB/s or over, you can see that here:
https://ram.userbenchmark.com/SpeedTest/1454553/Samsung-M471A1K43EB1-CWE-2x8GBThen, i checked speed of RAM on i5-11400 with other model laptop, in here is Asus tuf 15:
https://www.userbenchmark.com/System/Asus-ASUS-TUF-Gaming-F15-FX506HCB-FX506HCB/246244#Benchmarks And so surprise, it almost has over 15GB/s with single channel DDR4-3200MHZ:



With dual channel DDR4-3200MHZ on tuf 15, it has over 30GB/s:

I also checked speed of RAM on laptop Acer nitro 5 AN515-52 with CPU i5-10300H, the processor support bus RAM 2933MHZ. In here:
https://www.userbenchmark.com/System/Acer-Nitro-AN517-52/191134I got some results. With single channel DDR4-2933MHZ, the speed of RAM is over 15GB/s:

With dual channel DDR4-2933MHZ, the speed of RAM is over 30GB/s:



And you can also see the speed of single channel DDR3-1600MHZ RAM:
https://ram.userbenchmark.com/SpeedTest/90810/GSKILL-F3-12800CL9-4GBRL-1x4GB . The speed is approximately 10GB/s.
The speed of dual channel DDR3-1600MHZ RAM:
https://ram.userbenchmark.com/SpeedTest/50785/Crucial-BLS4G3D1609DS1S00-2x4GB . The speed is approximately 20GB/s
From all of the above, I come to the conclusion that: has some error with i5 11400H on AN515-57, it cause the speed of RAM not reach the maxium, the speed of RAM is just ~ 1600MHZ.
I hope acer will release an update to fix this soon.
P/S: My English is not very good. I hope you can forgive me.
Thank for reading!!
//Edited the content to add model name.