Air cooler clearance of the 5000X: 170mm - subtract 1mm off to err on the safe side, in regards to the cooler contacting the side panel or possibly preventing it from closing.
PA120 height: 157mm. Front fan sits over some dimm slots. The fan can be raised, which increases total height, but ram clearance in its default position is not stated anywhere.
DRP4: 163mm. Front fan situation is similar to the above, but there is an image of the DRP4 paired with a G. Skill DDR4 Trident Z kit, and that's 44mm tall... the fan clears that in the default position.
You should also know the height of the ram you're purchasing, because that will influence how high the front fan will need to be raised, if at all.
From the above, we can deduce that the DRP4 has better ram clearance than the PA120, but you only have about 6mm of extra space to raise the front fan if the chosen ram kit is taller than DDR4 Trident Z.
With the PA120, you theoretically have about 12mm to work with, assuming the fan clips don't run out of tracks to clip onto first.
There are models that don't hover over the ram, like:
NH-D15S
FUMA 3
Assassin IV, AS500, AS500 Plus(it's an AS500 with an extra fan)
Silver Soul 135
Maybe consider one of those instead?