Which M.2 slot to use

I have the Asus B660-i and a Samsung 980 Pro in a Thermaltake Tower 100. I have the SSD in the top slot with the Asus heatsink. I'm wondering if I should move the SSD to the back of the mobo. I'd lose the heatsink benefits but it then would be inches away from the 140mm Noctua exhaust fan.

The only difference I see in the manual besides the heatsink is that the back M.2 slot mentions Optane but the top doesnt.

What would you do?