different PCB i'm 90% sure of it
i'd return it for exchange unless i am wrong. unsure

the 780 and ti pcbs are the same as the vanilla titan sc. when in doubt. clean all the surfaces and just dry fit. dont srew anything down but put the plate and cooler on the card and see if the screw holes match up. im almost 100% sure these are the same pcbs

ill make you a deal send me your 780ti and ill install my titan acx cooler on it and test it for you. ok?
 
 
 
 
 
 
 
j/k i wanted to make some one laugh. 

lol. the only reason im saying they work is because i had to contact frozen cpu because they didnt have a nickle ek block for my newest titan. as long as it isnt a classified ti they are the same pcbs. i had to buy a 780ti ek block for my titan. i hated that i had to do it even the backplate is gonna say 780ti . atleast its the bottom card. from what ive seen the classified have a wider pcb and what not.  but if you wanna do it im not gonna argue with that  

Apologies for reviving an aged thread but can anyone verify that a ACX Titan Black Cooler will fit on a EVGA Titan Superclocked?  I am getting mixed answers from EVGA (and from other forums)  .....thanks in advance for everyones replies!