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.
Anyone know if the NHL12S fits the Asrock X570 board in this case?
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?