Because most people who are mining Bitcoin with ASIC instead of GPU as GPU mining is completely unprofitable.
Unless you are mining as a hobby, mining with GPU is better suited toward Scrypt, i.e. Litecoin or other Scrypt cryptocurrency, rather than on SHA-256.
If I were to start mining Litecoin or something similar, wouldn't it use my GPU the same way? Or would I be wasting power by ocing it then?Unless you are mining as a hobby, mining with GPU is better suited toward Scrypt, i.e. Litecoin or other Scrypt cryptocurrency, rather than on SHA-256.
Scrypt mining is completely different from SHA-256 mining.
Overclocking is not necessarily with Scrypt mining.
With your 7950 instead of hashing 550 MH/s it will hash at 550 KH/s
1/1000 the speed of bitcoin but that is how scrypt mining works i.e. 1 GH/s in bitcoin is like saying 1 MH/s in scrypt mining.
I suggest you should do some research on scrypt mining as it is a better choice for profit, unless you are mining as a hobby, you will NEVER profit from bitcoin by GPU mining.