I need some answers answered about radeon gpus.

[StarTrek2013]

I am tight on a budget so I am wondering which of the following:
-Am I going to notice that much of a difference between a 7850 and a 7870?
-Does it matter if it has 1gb or 2gb? I am going to be playing call of duty black ops 2 1020p on high settings. My cpu is FX-6300.
-Which will offer me more performance dual Radeon 7850 1gb or Radeon 7870 2gb?

 

[smeezekitty]

If you already have a 7850, getting a 7870 is not really worthwhile.
1 GB is usually enough but VRAM is getting more and more important
Two 7850 would be faster, if the application properly supports crossfire