So the Chimera is slated to have a CPU cooler clearance of 165mm.
The IceGiant ProSiphon Elite is apparently 165.9mm in height. From the prototype we've seen on LTT, this may be the best self-contained CPU cooler on the market when it launches in a month or two. https://www.icegiantcooling.com/prosiphonelite
This seems as though it should still fit, maybe contacting the side panel with slight bowing, though probably not safe for travel (it's about the same weight as a D15, so that may preclude it anyway). But it would be a shame to not double check that this is fully compatible, as there won't be a better workstation cooler period if the hype pans out (including mult-rad open loops, due to reliability, longevity, simplicity).
Well and I guess if the Chimera has no perforated top panel option, the point is likely moot anyway.
Agreed this will be great if it does fit.