You cannot use 4 GTX 295's in any setup regardless... Dual 295's is considered quad-sli... Second, dual 295's is OVERKILL so you would be wasting your money unless you are trying to break a record.... not to mention the next-gen cards are around the corner....
EVGA x58 does not support xfire...... If you want a board that supports xfire then you need to be looking at Asus, Gigabyte, Asrock, etc...... =)