Hi,
 
Long story short, I purchased a couple of 1080 Ti SC2 Hybrid's as B stock from EVGA. They are both out of warranty. I wasn't using one of them, but it had been in my PC working fine in the 2nd slot (I tested again before pulling out of my pc, running quiet, temps wouldn't exceed 50C under benchmark, pulled it out very carefully and repackaged exactly how it came from EVGA) Yesterday, I sold this to a guy from the local online classifieds and he took it home and then text me later that evening and told me it sounded like a lawn mower and as soon as he turns on his PC the noise starts immediately and then goes to 90C within 2 minutes of booting... 
 
I guess my question is if he installed the reservoir below the card, or put the radiator upside down would this cause the pump to instantly fail? I get that the pump needs water... but how did this go from working perfectly in my PC the day before to failing this terribly? Can this possibly just be air in the pump? 
 
Here's a link to a YT video with the sound that he sent me:
[tube] youtu.be/GaIZcOq47Do [/tube]
 
When I handed it to him, he pulled it out of the box, but when he tried to put it back in he struggled to get the hoses & radiator back in the box, wondering if twisting messed it up somehow or if it just randomly died? 
 
Either way its a major bummer. He finally text me after going back and forth trying to diagnose and wants his money back.... the problem is I didn't record it working properly before selling or I would probably tell him SOL. I feel we're both at risk buying/selling used computer parts and I haven't decided yet if I'm okay taking it back and eating all of it...
 
Any thoughts or advice would be greatly appreciated.
 
Thanks

Oh, you edited it! Lol.

I would suggest meeting up with him and looking at the card closely. Do you happen to have the serial number to verify he didn’t change anything about the card before you take it back?

Sadly, you may be out of luck, but it also could be something very simple. Check to make sure the cables didn’t get unplugged from the pump/card.

And look to make sure there is no fluid leaking from the hoses.

Jc,
 
Sorry for the really slow reply.
 
Yes, I took the card back, but only after a bunch of back and forth trying to diagnose/help him fix it and finally requiring the buyer pay me $50 to meet me halfway with the cost of repairing with a G12 & new cooler. I did preemptively purchase a Kraken G12 and a Thermaltake 3.0 Performer C along with some heatsinks so that when I got home I could just take it all apart and get it fixed all at once. However, I got busy and didn't get around to finally examining the card closer until this weekend, upon removing from the box I checked all the connections and I noticed that the person I sold it to had twisted the pump cords over each other at an awkward angle. I untwisted them/the cooler, played with the cooler a bit (to get coolant to move around etc) turning it upside down back and forth a few times and stuck it back in just to test before going the G12 route. To my surprise the card works fine and the noise is gone (tested thoroughly and temps do not exceed 51C in benchmark tests), the only thing I can think of is that his twisting the cords over each other at that angle caused the pump to be strained/not work correctly or maybe in addition to this he could have even had the cooler mounted upside down. He did mention it was his first time ever trying a GPU with an AIO... 
 
However, with this being said, I did quite a lot of research into the G12 along with trying to find a decent cooler to use. While I did not end up having to do it, I know that I found many people went this route and it solved their issues.