I have several M.2 drives on my Asus ROG Zenith II Extreme Alpha, and unfortunately the third slot is on the back of the board and has terrible cooling, with no room for full-size heatsinks. Attached is a picture, it's a pretty common place for some reason, although accessing the back of the motherboard is incredibly inconvenient. On my Sabrent Rocket 4.0, my temperatures (without the heatsink) went from idling at 55ยฐC peaking at 84ยฐC under Crystal Disk Mark to idling at 45ยฐC and peaking atโฆ