QI, the H50 has a set of stand offs that go between the motherboard and the retaining ring that prevent the retaining ring from putting much if any real pressure on the water block/pump. Mine would actually spin in the bracket fairly easy so I ended up not fully twisting the waterblock in so some little high points on it would grab against the retaining ring to help put more pressure against the cpu.
As for the surface of the water block mine was flat but was course on the finish surface, I cannot remember where it was but I seen where they where claiming that it allowed it to work like a pleated filter giving it more surface area and that is why they used such a thick TIM to fill in the area.
As for the surface of the water block mine was flat but was course on the finish surface, I cannot remember where it was but I seen where they where claiming that it allowed it to work like a pleated filter giving it more surface area and that is why they used such a thick TIM to fill in the area.