As you say, this is NOT a supported way of using this specific card. Try the following at your own risk…
Your best bet is to look at the consumer gaming rigs that people create. Depending on how much room you have in the tower, liquid cooling is pretty good and there are plenty of options to choose from. Here’s a company that I’ve personally used in my younger gaming days, the kit is very nicely made: http://koolance.com/ Using kit like this you can improve cooling on your CPU, RAM, Chipset, Hard drives, GPUs and even the PSU. You can create whatever kind of cooling system you need to do the job. Maybe a cheaper solution like this could work for you: http://www.corsair.com/en-gb/hydro-series-hg10-n780-gpu-liquid-cooling-bracket
If the above is too much and you just want to increase the air flow for the GPU, then alternatively you’re looking at something a little less involved like this:
And of course there are many different options from many different vendors between those solutions to suit various budgets. Your choice in cooling solution should depend on how hard you intend to push the hardware factoring in overclocking, ambient air temperature etc etc …
Have a look in the GeFore Forums for some inspiration: https://forums.geforce.com/default/board/52/cooling-and-case-modding/
and here: https://www.overclockers.co.uk/ and here: https://www.scan.co.uk/ for various cooling components
Note, these are consumer grade products, not enterprise.