It wasn't the watercooling. It was the missing sticker and small screw for a backplate that voided my warranty per EVGA. The item was not returned in its original condition.

"Hello,

I apologize for any inconvenience with your RMA. While you can install a waterblock on a graphics card without voiding the warranty, if you send the product to us for warranty service it does need to be restored in the original factory condition. This would mean that it does need to have the all screws reinstalled with the cooler/backplate and also needs to have the original manufacturing stickers still on the PCB of the graphics card. There should be a manufacturing identification sticker above the PCIe goldfinger connector of the card, but when we received this card it was missing. Due to this, we could not accept the product for warranty service. Unfortunately, if we are not able to accept it for warranty we are not able to provide any repair or service for the product. As we are unable to continue with the RMA, the product would be returned to you in the condition in which we received it.

If you are interested in purchasing a graphics card through EVGA.com, we do have an associates code available. You would want to enter associate code: [edited] during checkout to receive 5% off of a graphics card purchase. 

Again, I apologize for any inconvenience with your RMA and please feel free to contact us if you have any further questions.

Regards, EVGA"