Assuming a cable area of 0.205 mm² (cat.5) which gives 0,188 ohm/meter and 5 V with a 5% tolerance. Ohms law U=R*I gives the maximum cable length to be 2,2 meters. Quite tight.
I hope the next board at least has space to populate it with onboard 5 V regulation.
Are you talking about the length of copper wire between the board and the AC/DC converter that plugs into the wall outlet? Or the total combined circuit length of the board itself? To a FPGA board-designing geek, your question is probably quite obvious, but to a novice like me, it isn't as clear. LOL