I believe the 4090 requires either an ATX 3.0 P/S or a 16-pin adapter cable. ATX 3.0 has a 12+4 pin power cable, whilst the adapter cable requires 3 x 8-pin connectors dedicated to the cable. The Corsair has 1 x 8 pin, 1 x 4+4 pin, and 1 x 6+2 pin connectors. You need (at least) one of those for your motherboard, leaving you short. It is not recommended to use a pigtail to add connectors to a single modular socket.
If it was me I would spend the money (including customs fee or whatever) to source a P/S that meets the new ATX 3.0 spec, and includes a 16 pin cable.