My hands are cold and I want to get back into bed. So I'll try and be brief posting this one. I put my old Kraken G12 I bought last year for my RX 5700 (which I sold and replaced with an RTX 2070), and my even older Corsair H75 from a few years back, on my RX 590 (the XFX Fatboy card).
I couldn't fit heatsinks on the GDDR5 memory chips due to clearance issues with the cooler's pump block, but the 8 Gbps GDDR5 chips should be OK to run without active cooling provided there is some airflow over the chip packages and I don't overclock them too much. (I don't overclock them at all, because they don't really overclock that well anyway).
I explain most of it in the video, but the long and the short of it is, it was really cold in my room (~ < 10*C ambient) because I had my skylight window open, and the fan on the radiator is spinning constantly at 3000 RPM. Idle temperatures on the GPU core were in the 12-13*C Range and under load, 37-38*C, even at 1.2V and sucking down nearly 200W. Which is really impressive. My fingers are going to snap off soon because it's still that cold in my room so without further ado, here is the video link on my OneDrive.
I also test RX 480 and 580 clocks (1266 and 1380 MHz, respectively) to show performance gains between the 480, 580 and 590, along with the overclock of the latter).