Can I Run two different Ram Sticks that are just slightly different?

[Shadowdiamond201]

I Have a new computer and was planning to take the ram from a slightly older computer and use that in the second ram slot. 
The model number off the RAM in the new computer is M378A1K43EB2-CWE
and the Model Number off the RAM from the old computer is M378A1K43CB2-CTD

Main difference I see between the two is the one is a slightly slower speed at 2666 MHz while the other is 3200 MHz

[Radium_Angel]

Yes, the faster RAM will downclock to the slower sped.

DOn't try to use XMP or OC it though

[asheenlevrai]

It should  work (both modules would run at 2666MTps) but that would be a waste (especially if you're running Ryzen which greatly benefits from RAM speeds between 3200 and 3600). RAM is cheap these days. Maybe buy a 2nd 3200MTps module (ideally identical to the one you already have) and retrieve whatever you can selling the 2666MTps module.

[Somerandomtechyboi]

Basically you are trying to combine 8gbit samsung e die and 8gbit samsung c die

 

I dont see why it wouldnt work at 3200c22 jedec but it problably wont go much past that cause c die is hot garbage and 8gbit e die is apparently kinda meh, the 4gbit stuff is really good as in usable for oc even in 2133 oem sticks like m378a1g43eb1 + decent subtimings and 2v+ scaling