+You don't by chance know how Amazon returns work? lol
I too just bought the GTX 780 6GB two weeks ago from Amazon. I am going thru the same dilemma . . .I was very excited about the 6GB 780. . . Now a 980 !!!!
Well. . . From what I have read and been told by techies at the computer store the 980 is better because of the new technology in it even though it has 2 less vram. The 780ti only has 3gb but has more cuda, more bandwidth and is faster. The 6gb is good for certain applications like video editing and some games But the 780ti is still faster and better BUT Also more expensive. NOW the 980 is on par with the 780ti according to releases benchmarks. If accurate. In some tests one is better then in others the other is better. But the 980 has 4gb which is better And is Cheaper than the 780ti. . . .also the 980 uses less power and has many other new technologies in it that makes it so fast with less cuda cores and bandwidth and it is still neck and neck with the 780ti.
Well. . .I am returning my 780 6gb to Amazon since they give you 30 days to return. You just need to log in to your acct with them and go to your orders page , click the boxes for the returning item and follow the instructions to mail it back. I am a little sad to send the 780 6gb back - I was really excited to get it. . . But I read the info on the 980 and picked one up this afternoon. . . .sooo I will see how it is. . . .Good Luck !!