Keep or sell my 680 or 6990

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I'm currently running a WC 6990, but I recently brought a msi 680 gtx lightning and water blocks for a planned upgrade for SLI setup but didnt buy the 2nd card and doubt I will anymore, now i am thinking of selling or maybe switching to just one 680.
My question is which is the better card 6990 or 680 lightning? Gaming @ 1440p
Thanks

 

[Rated_R]

I was planning to get both cards before taking apart/cleaning WC systems and then switching over to the WC 680 lightning SLI then sell the 6990.
I don't think anywhere sell any 680 lightings anymore so not sure if its worth keeping the one I have now...

 

[Rated_R]

lol but I have 2 lightning WC blocks... just need 1 more lightning card though.