Okay, I understand. Always good to use what you have! I think you should be fine with the NH-L9a. Please let us know how it goes.
After looking at the photos @Analogue Blacksheep posted in the other thread, I don't think it will fit in the orientation that you would want in the L5 at least. Maybe with it hanging over the DIMM slots?Anyone know if the NHL12S fits the Asrock X570 board in this case?