When attached to a motherboard's PCIe x16 slot, a card such as the GeForce RTX 4080 can draw up to 75W from the +3.3V and +12V rails (3.3V x 3A + 12V x 5.5A). This is the maximum amount specified ...
For starters, the RTX 5090 FE features three PCBs rather than one large PCB, one for the PCIe 5.0 x16 connector ... boards have been connected via ribbon cables to not interfere with cooling.