Managed to improve the sound levels on the Peerless Assassin, it still has a slight whine at the top end but it’s better.
I was trying to be clever with my fan placement and as always, that’s a terrible idea. This cooler has 2 towers and 2 fans so there’s 3 spots you can put them in. I thought I’d avoid covering the RAM slots and put them towards the rear of the case. The last one even slotted perfectly in the gap above the IO block. 1/2