I'd use a pico fuse until you can get hold of an SMD. The 5V pad is
probably
straight into an internal power plane on the capable of sourcing the full
power of the PSU 5A rail. No fuse on the motherboard, but the PSU might
shut
down if you have a hard short.

I think the fuses should be 500mA. That's the maximum rating for a USB port.
But it might also differ for different boards. The fuse is not there to
adhere to some standard, the fuse is there to protect the motherboard.

PeterV