Mixing up RAM?


Apr 12, 2017
So not late ago, I had one of my ram sticks die on me. I had the following ram:
2 x 4GB DDR3-1866 SODIMM Corsair Vengeance GX3M2B1866C10

Now I'm running on only one ram stick and quite honestly 4gb feels very sluggish on a 64bit windows 10. I was thinking about upgrading my ram and I checked the prices. It turns out it is much more better to buy an 8gb stick than a 4gb stick due to cost difference being small.

Due to my processor being an i5 that only supports up to 1600mb/s while the ram I was shipped with was 1866mb/s (a mistake when I chose) my effective speed is 1600mb/s. I know mixing up ram brands and sizes is bad, however I'd much rather buy an 8gb stick and try if it works with my old stick (if it doesn't I'll just remove the old stick) rather than just buy 1x4gb stick for the same price which might not work as well (because finding my Corsair ram on internet is super hard).

So I was wondering, which specifications for ram sticksdo I need to look out for my DDR3L 1866mb/s 4gb 1.35v Corsair vengeance?
Also, my manufacturer long ago told me this:
"GX3M2B1866C10 ( the "2B" in the part code is important as it will denote the correct type that is compatible with the machine. if it says "2A", don't get.)" Is that distinction between 240 pin ram or mobile ram or is it even worth looking out for?
You should buy a new 4GB DDR3-1866 SODIMM stick, so you can have a dual-channel setup. It will be a bit faster than a single 8gb stick.