If you feel 8 GB is better for the performance of your system (given what you do with it), buy a 2 * 4GB set like the ones from http://www.crucial.com/usa/en/compatible-upgrade-for/MSI(MicroStar)/x58a-gd65
I currently have 3x2GB = 6 GB of Corsair Ram. I have 3 more slots in my motherboard (MSI x58a-GD65 MS-7522), so im thinking to increase it to 8GB (an additional 2 GB stick). But I am not sure what my current RAM speed is, and I know that what I will buy has to synchronise with the existing ones. I am attaching a screenshot from my PC, please tell me the exact model, type and speed I would need to buy. PS PLEASE TELL ME IF THE IMAGE IS NOT VISIBLE.
from CPU Z PROGRAM
from CMD prompt