Asus Sabertooth 990FX has 6x PCIe with one nearest CPU missing so any of the big coolers will fit.
Gigabyte AMD X470 Aorus also has plenty of room.
Any cooler will fit as long as RAM is not too tall.
Enthoo Primo has 30mm more CPU clearance (207mm) than tallest cooler I know of and all kinds of airflow so no problems there.
Before suggesting coolers I'll tell you I always do a practice install on any cooler I'm not familiar with. It only takes a few minutes and usually saves lots of anger and frustration .. not to mention TIM ending up where it shouldn't be and/or a bad TIM print. I also use kitchen paper towel cut into 5cm squares and isopropl alcohol for cleaning. I wipe what I can get without problems onto a piece of towel and put it in the bin before the TIM can jump onto anything else. I swear there are TIM jumping gremlins.
Probably the best out are Thermalright Le Grand Macho RT and NH-D15. Le Grand Macho RT is ever so slightly better at cooling and noise levels. It will clear tall RAM in front of CPU, but not behind. Also a little harder to install mostly because it tips over backwards if not held in place and mounting crossbar is not fixed to base and can move. Best to have a 3rd hand to hold cooler in place while installing cross bar and tightening, but I do it all the time solo.
The best lower priced which is within 2-3c with one fan is TRUE Spirit 140 Power. It has 6x 8mm heatpipes. It is maybe 2c warmer with 1300rpm fan than D15, but D15 has 1500rpm fans, and that is worth at least 2c.
|It clears RAM front and back of CPU
Cryorig R1 Ultimate and Universal are very good too, but I don't like their fan sound as well as TY-1xx series fan. The Universal clears all RAM and has base offset 5mm more back than Ultimate and also a 14mm thick front fan instad of normal 25-26mm front fan.
Noctua NH-D15 is good but usually more expensive than others. While cooler will clear tall RAM front fan still has to be set on the RAM so ends up looking too high.
D15S has offset base for better PCIe clearance.
NH-U14S is also good, but almost as big a TRUE Spirit 140 Power, costs more and doesn't cool any better than TS140P.
Phanteks PH-TC14PE is good too. The original had 2 piece soldered to heatpipes but they changed a year or so ago to 1 piece fins with no public announcement of change. Only way I found out was someone bought one and asked me if it was a counterfeit or real. I had to ask Phanteks rep who had to ask headquarters because he hadn't been told about change either. I tried to get one of the new ones to run comparison tests but Phanteks told me they cooled the same .. and I have seen no reviews that reviewer had newer one piece fin cooler, so no independent verification.
be quiet! Dark Rock Pro 3 and new Dark Rock Pro 4 are good and quiet, but not any better (2-3c warmer but very quiet) than others but look great.
The river website has Thermalright. Can't say any more because OcUK doesn't like us telling prices elsewhere.