RAM - memory module dilemma

After trying VMs and Containers, I see the purpose to max out the memory in my NAS.

I know some things are better than others with a reasonable toll. What I see now.
I need 2x16GB ECC
(per module)
Synology D4ES01-16G DDR4 2666MHz ECC Unbuffered CL19 - $350
A-Tech DDR4 2666MHz PC4-21300 ECC Unbuffered 2Rx8 1.2V - $75
v-Color DDR4 2666MHz (PC4-21300) ECC CL19 1.2V - $75
QNAP DDR4 2666MHz ECC - $300

For the number of available memory slots (per my understanding), there is no big difference in usage unbuffered vs registered, the only difference the latter is less expensive. Looking at the prices, I cannot understand x4 price difference.

Did anyone try to put 64GB (2x32GB) into DS923+?

My dilemma is that going with A-Tech I can use a reminder for APC Smart-UPS SMT1500C.

I found the modules very similar to Synology by description and the form factor. $52.

At the same time, I learned more about ECC. :slight_smile:
Dual ranked - twice as many x8 chips. It is similar to Synology D4ECSO-16G.

Then another one which is similar to Synology D4ES01-16G has this features
On-Die Termination (ODT) - termination of noise
Serial Presence Detect (SPD) - a standardized way to automatically access information about a memory module.
Single rank
Sixteen banks

Does anyone have a picture of a real module D4ES01-16G?

I found a reliable maker and a good site to order.