this is what you need: http://ttpremium.com/product/water-3-0-series-aio-liquid-cooler-am4-bracket/
Oh sorry I answered before I had a look at which motherboard you were using, that motherboard has special mounting holes and supports AM3 coolers out of the box, without replacement brackets etc. https://www.asus.com/us/Motherboards/ROG-CROSSHAIR-VI-HERO/ scroll down this link until you see the title extended compatability.
this is what you need: http://ttpremium.com/product/water-3-0-series-aio-liquid-cooler-am4-bracket/
Oh sorry I answered before I had a look at which motherboard you were using, that motherboard has special mounting holes and supports AM3 coolers out of the box, without replacement brackets etc. https://www.asus.com/us/Motherboards/ROG-CROSSHAIR-VI-HERO/ scroll down this link until you see the title extended compatability.