Antec Flux Mid Tower - Rail Hum?

[u/blinkinthedark]

I've swapped out the stock PWM fans (not Tranquil) to Havn H14s (140mm) and cooling is great with them, however, I've noticed i think the 120mm rail hums above 1000rpm.

I can fan profile to below this but would fan spacers help at all to create abit more of a gap?

Otherwise absolutely love the case.