I need help with upgrading my RAM!

[mihaifrmgs]

So, (I know this question may sound dumb) but if I have a 4 gb stick of RAM in my PC can I get another stick 4 gb of RAM or can I only use an 8 gb stick to upgrade?

 

[markoroga2001]

Firstly bouth of your sticks need to have same ddr (ddr2, ddr3 or ddr4).
It would be better if you have 2 sticks of 4gb with same Mhz, but it' s okay if they do not have same Mhz than the higer Mhz stick works on lower Mhz stick frequency.