Hello!
 
After months of waiting, I have finally managed to put my hands on a second hand EVGA 1080Ti FTW3 Hybrid on eBay which arrived this Friday.
 
But as soon as I took a look at the back plates when unboxing it, I have seen some kind of fluid between and on the joint of the two back plates. It is not a huge puddle but it is enough to clearly see it. If I wipe it and let the card on a table (the back of the card facing the surface), I can see stain coming again.
 
You can see pictures and videos illustrating that I am saying from here:
drive dot google dot com slash folderview?id=1k-izUhDuHxb_sK6DARjy-uyLUK7ARPyu
 
The seller claims to be the original owner and said that he bought it on Amazon in the beginning of this year (2018). But I did not received the original invoice (nor the copy of) with the packaging as I have asked him when ordering.
 
Now, my questions are:
- Can a cooling liquid come to this side of the card? How?
Is this actually a water leak? If not, what is it?
- I read that EVGA does not support physically damaged card. Does this dammage fall into this category?
- Will EVGA RMA this card if I choose to keep it?
- The seller is nice and offered me a free return. But does EVGA's warranty service refund shipping costs?
- And finally who can help me to know the remaining warranty on this card?
 
I will be glad to anyone who can help me to decide if I send back this card to the seller or to go on a trip with EVGA's RMA teams.
 
 

HOW can I know if the card is still on warranty?

As the seller gently offered me a free return, I do not want to unscrew and remove the back plate, nor to touch anything else on this device, especially if it turns out that it is really a water leak.

Plus, I do not understand why EVGA does not support water leaks. Should not a brand replace or repair a product if a damage on it is related to the manufacturing quality or design defect?

The tech I think provided the best answer. It's enough of an issue to make someone worry so for that reason I would recommend going back to the seller on it for the refund.

If it was a liquid leak, wouldn’t it be on the front of the card?

More than likely, everything you see is from a thermal pad on the back of the card, since gravity works in a way to where the liquid would not be able to go up through the card from the cooler, and then travel to a completely different location of the card. Even when vertically mounted, liquid from the water pump shouldn’t be able to get to that location.

The thermal pads, however, are under pressure between the backplate and the pcb, so it would be able to squeeze through openings.

Thermal pad grease is 100% normal, not a sign of any abuse at all.

It just happens when the card warms up and then cools down.

Sellers purchase date wouldn’t change much for you. Cal tech support for your region when you have time, and request that they look up the remaining warranty if possible.

I got an answer to my email and the remaining warranty period is OK!

Now my only questioning is the thermal conductivity (in W/mk) of the factory installed pads and their thicknesses in the 1080 To FTW3 Hybrid. What will I need to buy if I want to replace (all of) them in near future? Will a 100 x 100 mm pad will be enough to replace all of them if the thickness is the same for all?

the_Scarlet_one
...
It just happens when the card warms up and then cools down.
...

Even if the card was not in use for weeks? Right out of the box? I did not plugged it in since I received it and the grease come back every time I clean it up.
That is why I prefer to clean this pad in priority and replace it.

So, if somebody else looks one day for the same informations:
- the closest answers to thicknes of pads are:
https://www.evga.com/support/faq/afmmain.aspx?faqid=59738
https://www.evga.com/support/faq/afmmain.aspx?faqid=59664
- no official value about their thermal conductivity but I have read here and there that "they are" 1 or about 3 W/mK 
 
Many of the replacements pads I have found are 100x100 or 120x20 and You will have to dissasemble Your card to see how many of them You will need to buy to suite Your needs.
 
The following is a list of some not extremely pricy pad models with a W/mK >=5:
Phobya Ultra 5W/mK , 100 x 100 mm
Arctic Cooling ACTPD00005A 6W/mK , 145 x 145 mm
Alphacool Ice Layer Light 7W/mK , 100 x 100 mm
Phobya XT 7W/mK , 100 x 100 mm
Thermal Grizzly Minus 8W/mK , 100 x 100 mm
Alphacool Eisschicht 11W/mK , 100 x 100 mm
Gelid GP-Extreme TP-GP01-B 12W/mK , 80 x 40 mm

Phobya Ultra 5W/mK , 120 x 20 mm
Phobya XT 7W/mK , 120 x 20 mm
Alphacool Ice Layer Light 7W/mK , 120 x 20 mm
Thermal Grizzly Minus 8W/mK , 120 x 20 mm
Alphacool Eisschicht 11W/mK , 120 x 20 mm
Alphacool Eisschicht 14W/mK , 120 x 20 mm
 
Also:
EKWB 3.5 W/mK
Fujipoly Extreme X-e 11W/mK
 
If someone has mpre precise values about the 1080 ti FTW3 Hybrid, do not hesitate to share Your knowledges.
 
Thanks again to all the ones who helped me!