I have 3x 1080ti hybrids in my case.  All have been working great for 6 weeks.  Max around 60C. Today I noticed my third card was at 90C!!  I removed it then my second card went from normal to 90C. Like the pumps decided to stop running.  Is there anyplace to actually see pump RPM?  
EVGA GeForce GTX 1080 Ti SC2 HYBRID GAMING, 11G-P4-6598-KR

I agree, but I've read posts of EVGA cards doing things like this apparently....  or running intermittently.  I am installing the latest version of nVidia drivers but I'd imagine this is controlled by firmware not drivers?
 
I'll try the tube idea.

To be quite honest I'm not sure if my second card was "normal" in hind sight.  Maybe that was my own hopes and dreams that it was somehow software.
 
I can feel vibrations but they are different than my good card. Only the tube going to the radiator gets hot which indicates low flow.
 
Looks like I am going to have to RMA both cards.  Really sucks, I've never had issues with a video card in fifteen years and this was my first time I went with EVGA.... and I build multiple rigs a year.
 
Oh - and no pump info on precision X.  There's only one card here because I pulled both when I saw they were hot. I put one back in to troubleshoot more.

I was able to attach a picture in the previous post when I used edit.  It is really strange both cards went hot at the same time... I even purposely lowered the temp to ensure no long term issues.  
 
Support suggested removing and gently shaking (I guess for air bubbles).  It didn't help.  All my radiators are mounted above the cards in accordance with the instructions so that shouldn't happen anyways.

How are the hoses orientated on your radiator ?
 
My 1080Ti FTW3 Hybrids, need XOC running
 
Your 2-GPUs factory Hybrid or conversion cards ?

It’s normal to pay shipping back for RMA’s. It’s not fun, or cheap, but you may be able to package both cards and include both RMA paperwork and RMA numbers on one box to help keep the cost down some.

Anyone know if my cards are the same layout as the reference PCB incase I wanted to just buy waterblocks?
 
EVGA GeForce GTX 1080 Ti SC2 HYBRID GAMING, 11G-P4-6598-KR

Dayaks
Anyone know if my cards are the same layout as the reference PCB incase I wanted to just buy waterblocks?
 
EVGA GeForce GTX 1080 Ti SC2 HYBRID GAMING, 11G-P4-6598-KR

Looking on ekwb for your card they don't make a block for it or the regular non hybrid sc2 card. Looks like the regular evga sc card is the reference design.

No idea what's different between the sc and sc2 evga cards.

So where is the pump located on the hybrid in stock setup? Isn't it on the part directly attached to the card? 
So how does that work? Just not power the stock pump and let the aftermarket pump push around the free spinning stock pump?
I assume you can't remove stock pump it if it's built into the waterblock. just curiosity taking over now.

bdogg454
So where is the pump located on the hybrid in stock setup? Isn't it on the part directly attached to the card? 
So how does that work? Just not power the stock pump and let the aftermarket pump push around the free spinning stock pump?
I assume you can't remove stock pump it if it's built into the waterblock. just curiosity taking over now.

Just put it in series with the existing pump. The temps are about the same (slightly lower but may be because of ambient).  I didn't want to try removing the existing pumps. I assumed they are epoxied or sonic welded and impossible to open anyways.
 
So yeah, just put an aftermarket pump in series and used some brass 1/4" splicers (male to male) connectors from Home Depot for a few bucks (and some hose clamps).  You can basically add anything (radiator, ect.) by just splicing it but you need to fill it properly with the proper liquid, ect. 
 
EVGA support was excellent but I can't be bothered to RMA. I had parts laying around anyways.

BOLD & Interesting approach - necessity is the mother of invention
 
Keep us updated on how this works for you longer term.
 
Did EVGA confirm what type of liquid was in the factory cooler ?
 
Did EVGA confirm what type of metals are in the factory cooler ?
 
What is the hose ID ?
 
 

Not sure if its Aluminum
 
Pure distilled water & Aluminum --> not the kind of testing I'd like to do

Sounds like a good solution.   Hopefully it lasts a long time.  When you put them in series like that, do you run it through one card, a radiator, then the next card? 

Welp,

Third and final card crapped the bed. Tomorrow I am going to say hell with it and throw in my good mcp655 pump and 9x140mm rad. Run all three cards off it.

I checked it at multiple times and the card was always at 59C, which is great, so beyond me why they all crapped the bed. Noticed it was slow a few minutes ago and it was at 91C. I am imagine EVGA will have a batch of RMAs on their hands though.

Oh also - 1/4" fittings.

Slap a ek 1080ti block on it in a custom loop and forget about it.

I get 31-33c on load with a ek 120.3 rad. 22c idle.