Acer Aspire E5-573 not recognizing second dimm.

Vlahotic · October 2016

So the problem is that my laptop does not recognize both ram sticks when I put them in together.
I have a 4GB stick that came with the laptop and I had another 2GB stick lying around and decided to do a minor upgrade. Alas, I don't see 6GB of ram when I boot up. The system (and the bios) only recognize 4GB (the original stick that came with the laptop).
I have tried

switching the sticks around
booting up with only 2GB stick
booting up with only 4GB stick
4GB stick in other laptop
2GB stick in other laptop
4GB stick from other laptop in both slots

All of the above yelided no results, in the way that everything was fine when I tried any of those. The laptop booted up every time, and the other laptop (the tester) booted up with all of the above mentioned sticks. So I guess it's not the sticks, or the slots?
The fun thing is that the task manager, system manager and bios all show only 4GB while CPU-Z shows the full 6GB and sees both sticks.

So is it because of the mismatch of the speed, of the cas or of the voltage?
If so should I generally just be better to get one 6GB or one 8GB (1.35v ??)?

philetus · October 2016

Your 4GB dimm is PC3-12800, 800MHz which is correct and your 2GB dimm is PC3-10700, 667 MHz which is incorrect and is not going to work. You need both dimms to be PC3-12800, 800 MHz.

Memory is available in 4,8.16,32GB, there is no 6GB dimm.