What's a better value - 770 or 780?

Palidion

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Jun 19, 2013
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http://www.newegg.com/Product/Product.aspx?Item=N82E16814130942
http://www.newegg.com/Product/Product.aspx?Item=N82E16814130945
I expect the price of the second card (the GTX 770 4GB) to drop to $400.

So my question is this:
Which one is the better value for the dollar? I want to SLI in the future, and was planning to go with 2 770's. . .but damn, a $500 780? What do you guys think? Thanks in advance :)

I'm looking for info regarding "future proof" status of both cards, overclock-ability, and whether I'd get more performance for the money going either way.
$400 GTX 770?
$500 GTX 780?
 

Palidion

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Jun 19, 2013
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Is that 20% less cost considering that it's $400 vs $500?
I'm not doing 2GB of VRAM.

EDIT: Nevermind. obviously 400 is 20% less than 500.
So is that 15% performance the same if overclocking is taken into consideration? I understand that the 780 is basically a crippled Titan and thus very overclockable, while a 770 is a 680 that's been rebadged?