I have Asus P8Z68-v PRO motherboard and was wondering there are 2 chasis fan connectors and 2 power fan connectors. If i have 4x120fans with 2pin connectors can I connect two of them to power fan connectors? Is there real difference between them?
No real difference, although the power rating for the fans you have may be a little different than what the mobo supplies, which may lead to the fans either working a little slower or a little faster, depending on the voltage and current supplied by the Mobo Fan headers.
And yes, you can connect them to the Mobo headers , they'll work fine.