can i add cooler master hyper h110r cpu air cooler without having to take out the motherboard from the gigabyte ac300w rev 2.0 cabinet?
CM hyper h110r ? Did you mean CM Hyper H410R ?
Gigabyte ac300w rev 2.0 cabinet has cutout for accessing cpu cooler area. It will be necessary for installing cpu cooler backplate. So yes - no problem.