I want to use this Sea hawk x cooler because I want a water cooled gpu but I don't want to get a 1080 Ti because they are very expensive (for me). so I want to get a 980 Ti from EVGA but I don't know if the 980 Ti and 1080 Ti mounting holes are in the same spots. I've looked at pictures of the founders editions of each cars they they look to be the same but I don't know for sure. If anyone has both cards and know if they have the same mounting hole please let me know.

I don't know 100%, but I would suspect it won't be compatible.  Best thing to do is contact EVGA and ask for their opinion.  https://www.evga.com/support/custsupp.asp
 
https://www.evga.com/about/contactus/
 

every series that the DIE changed size (got bigger) the bolt pattern of the 4 mounting screw also got bigger
 
Cooling is needed for more than just the GPU Die (AIO pump) .... so the odds that the cover, heat sinks & other parts fit is probably Zero
 
I'd have checked if I had any 900 series cards on hand ...... as I do have a couple of EVGA 1080Ti S FTW3 hybrids laying around
 
Ask, MSI

do the 1080 Ti's work?

Landvader07
do the 1080 Ti's work?

If both MFG's cards are reference designed PCBs .... then maybe it will work
 
There are too many variables in card design & mfg.  This includes component layout & heights above the PCB
 
So mixing coolers from different brands even in the same Series of GPU (1080 in this case) .... is an experiment
 
The Mfgs do Not publish enough detail information, to say one way or the other - with a high confidence level, if it will work

But do the cards work? will they display an image? or are they just for decoration?

Landvader07
do the 1080 Ti's work?

Landvader07
But do the cards work? will they display an image? or are they just for decoration?

 
I thought your question was about using a cooler from one brand of GPU on another brand of GPU
 
1080Ti is still a nice card

the 1080 ti is a really nice card. it still runs games at high setting today. you should hold onto your 1080 ti's. they are worth a lot.