You probably:
A)Just need to replace the thermal paste and pads on the card
B)Fix your airflow situation
C)A combination of A and B
D)Do nothing, because there's nothing wrong with 80C on that card.
To custom cool a gpu, you need:
-a water block that fits(check compatibility!)
-pump and reservoir, or a pump/reservoir combo
-a radiator and fans - don't just go out and get the cheapest rad and fans you find; they need to be 'compatible'
-tubing to connect the water block to the pump & reservoir/combo
-fittings - 2 for each piece in the loop. A drain valve would be lovely
-premixed coolant, or distilled water + biocide
-to have done your homework on the matter; do not dive in blind
To cool a gpu with an AIO, you need:
-a kit. NZXT's Kraken G12 is one of the more popular kits of only a couple(?)
-a compatible radiator. The Kraken G12, for example, is only compatible with units whose OEM is Asetek; the mounting system is fortunately, universal across the different generations
-to do your homework here too. It's not as much as the custom one though.
There's also custom air cooled solutions, like Arctic's Accelero Extreme and Rajintek's Morpheus.