Urgent - What is this cable for ?

[CasTex]

I have a problem. I purchased 2015 gtx 260, The transparent yellowish cable is connected to the coolant cup,

and the other side goes no where > https://i.snipboard.io/fRYoO3.jpg and https://i.snipboard.io/5NjpRK.jpg

Where should I plug it ?...

 

[POPPS]

Good news,,it just goes to the bottom of the hull.