Bitcoin(BTC) , bitcoin cash (BCC ) and now bitcoin gold are three different things in the bitcoin network. bitcoin cash was hard forked from the bitcoin network , because of the transaction speed issue of bitcoin ( it has a blocksize of 1mb and bitcoin cash has of 8 mb) .this difference in block size made BCC transaction faster than those of BTC.
now one cannot mine bitcoin or bitcoin cash using a GPU . to mine you need powerful dedicated servers. the algorithm which bitcoin uses is SHA256 , which cant be mined with a GPU . the miners who are supporting second hard fork i.e. bitcoin gold share views to open mining to more participants. they will replace the bitcoin algorithm to one which can be mined by a graphic cards .
bitcoin gold will implement equihash algorithm , which is optimised for GPU. with this , anyone literally with a graphics card can now mine bitcoin gold .