Is an "i7-3820 3.6Ghz" a Bottleneck for an 2x "GTX 980" System?

Solution
No, not really. There isn't much you could move up to aside from an extreme edition i7 or a 4790k anyhow. That CPU should be fine for GTX 980 SLI.

In fact, you could likely use that with three or four cards, without issue.