I just installed the new Arctic Liquid Freezer III 280 on my AMD 5950x. It is a beast of a cooler. In an OCCT stability test with all 16 cores engaged at 100% workload my CPU sustains 4.5 GHz with a maximum temperature of 63°C, and that's in a warm room (the aircon is broken). There are some reviews showing that it is less effective on Intel CPUs (no idea why) but for AM4/5 it's top tier.

But you are going to hate the AM4/5 installation process. The cooler plate attaches to the mounting bracket by means of a leaf spring, which is a curved metal plate with a captive screw on either side. Because the spring is a curved metal plate, when you thread one side the other will lift up, which puts the second screw into a non-vertical position, ie. not aligned with the hole. You need to try and push the second screw into a vertical position with your thumb while holding the leaf spring flat while locating the second hole, which you can't see because it's under the spring, and all this while the cold plate is sliding around on the CPU because of the thermal grease acting as lube. It's maddening.

There is a trick is that makes it easier:

1. Tap the first screw as little as possible. Just thread it a bare minimum amount to have it hold. This minimises the amount the plate will lift up, and how much the screw will cant off to the side, and how much pressure you need to apply to bend the spring.
2. Get the second screw threaded a bit, not too much.
3. Work your way back and forth between each screw, progressively tightening them by a small amount, the rest is easy.

Due to the way the cold plate slides about while you are trying to get that second screw tapped, I would suggest not using conductive thermal grease. There is a very high risk some of it will scrape off and possibly cause a short on your motherboard. If you do use it, you definitely don't want to use an excessive amount.

The Arctic Liquid Freezer II 280 is an excellent cooler and I recommend it.