How are you using 4 dimms, if you bought 4gb's last week, and want to buy another 4gb's this week?
As for your question, if you bought the exact same ram, chances are you'll have no issues. It's not a guarantee though, but you'll probably be fine. That's assuming you are just using 2 x 4gb's sticks that weren't sold as a dual channel set.
Let me try to make this as clear as possible lol
I built my 1st pc today. Im using OLD RAM from my OLD COMPUTER till my new ram gets here
My new ram is 2x 2gb.
I want to purchase another 2x 2gb of the same modle
So i will have 4x 8 gb