I think your then stuck running the fan on the motherboard or you need to find a 3 pin fan -
seems if you look them up there are a few threads on this here and like at toms hardware on that issue . maybe be some better help in one of them .
look up something like this and determine what wires do what and you may change the 4 pin to the 3 pin plug and leave the unnecessary wire blank ?
https://superuser.com/questions/1126136/three-wire-and-four-wire-cpu-fans-whats-the-difference/1126155 thing is plenty of 3 pin fans in 120mm [cheap]
https://www.newegg.com/Product/ProductList.aspx?Submit=ENE&DEPA=0&Order=BESTMATCH&Description=120mm+fan&N=100007998 600035673&isNodeId=1
now I pulled the plug on my hybrid 980ti funny its a 2 pin from the card but a 3 pin from the fan so I assume a 3 pin fan male would fit in to the 2 pin female of the card [ same as 3 pin but one is blank ] so maybe something had changed for the worse on your 980ti hybrid ?
so for my 980ti hybrid a 120mm 3 pin should work direct / plug and play
sad thing is just another reason I wished I just gone with the MSI seahawk with its corsair h55 unit on it and everything is easy and cheap to get for replacement parts and all that where EVGA's kind leaves you holding the bag if something goes wrong on theres . [your buying another new card pretty much or going all aftermarket new cooler]