vertical gpu mount pcie

5000D is not going to work for you it only has 2 slot riser you need 4 slot for a 4090 there are a few cases that you can turn all the back

Any suggestions? Edit: The reason why I want to vertically mount the GPU is so that I can see the GPU shroudface through the tempered glass

40 super slot free Buy Lian Li Universal 4-Slot Vertical GPU Kit featuring Riser Cable Length, 4 x Full Height Expansion Slots, PCIe x16 Interface,

4x8 slot car layouts 4 extension slots that support thick GPU and mount at the position preferred Gen PCIe Riser Cable Includes a 200mm long PCIe Gen4 riser