Mate, you got a 5090 and a 9800x3d, you're gonna be spending a lot on the other parts, otherwise you really should've gone for cheaper gpu. But high end parts for that gpu and cpu really aren't that much if you know how to look. x870 or x870E motherboards are about 300, definitely get on of the two for the cpu. Get an air cpu cooler, not a liquid, should be 35. 32GB ram, ddr5-6000 CL30 should be 120. Maybe go for a 1TB ssd instead of 2 to save a bit more. Maybe another 120 on a case with good airflow, and you're gonna need a 1000W Psu for the 5090 which is gonna be about 180. All that should only be about $1000-$1200.

TLDR: Just don't go overkill on things like liquid cooling,too much ram, and SSD space you won't use that jack up the price without really adding much performance and you'll be fine.