Reading the ASUS product page http://www.asus.com/Motherboards/P8Z77V_LK/#specifications
the motherboard does not support ECC ram.
4 x DIMM, Max. 32GB, DDR3 2400(O.C.)/2200(O.C.)/2133(O.C.)/2000(O.C.)/1866(O.C.)/1800(O.C.)/1600/1333 MHz Non-ECC, Un-buffered Memory
This is fairly normal for a consumer board. ECC or Error Correcting Code ram is normally a server/high end workstation product. It normally is more expensive than the equivlent consumer product as it has special chips to detect bit errors (usually some kind of CRC). This requires a specific chipset logic, which is not normally present in the consumer chipsets (although the northbridge is now integrated these days, so it is not normally present in the consumer CPU).