nonsense, vapor chambers work in any orientation, just like heatpipes.
they work best when they are straight up, but the difference isnt that big
think about it, most VGAs use heatpipes and vapor chambers and they are upside down
the GPU is the highest point on a VGA heatsink, but they still manage to move the heat away from the gpu to the fins and we are talking about 200-300W here while cpus are at 65-85W these days. well, up to 140W for amd cpus...