I have 2x 4gb ddr3 1600mhz ram should i buy 1x 8gb ddr3 1600mhz ram to get 16gb ram? Do they fit together?
You want to try and match the size, timing, and speeds to minimize any conflicts with memory preferably the same make and model.
I used 2x2GB and 1x4GB at one point in time. I had to due to a mishap with an ebay seller. They were both G.Skill Ripjaws X. The two 2GBs were 1600 MHz while the single 4GB was 2133 MHz. I believe they had the same CAS but not sure about timings. It ended up working fine for me. OCd my RAM to 2133 MHz to match the speed of the faster RAM. Never had any problems with it.