There's no standard for EATX except that it's "bigger than ATX". So I'm using an X399 board as an example here.
The cable cover has to come off for this to work. While it doesn't fully cover the motherboard, there just isn't enough clearance for the cables to go, even with a 90 degree angled connector. Unless, that is, your motherboard has the ATX power connector built-in at a 90 degree angle. While I'm not aware of such a beast, it may exist out there.