They use a heatspreader (solid metal surface, the "top" of the chip) soldered to the actual cores. Then you slap a heatsink or water block on and tighten it down on the heatspreader with the help of a thermal interface material (metallic goo). The actual cooling done by the heatsink or water cooler is pretty basic and similar to what you'd find inside cars or home A/C units.

With "280 watts" you can still use an off-the-shelf Noctua air cooler or any number of all-in-one water coolers.