Yes, GPU mining is possible now on Q2C, but that is not as efficient compred to CPU mining as on Scrypt or MMC.
You could still mine with CPU with a reasonable income.
not as efficient ?
A 3930K, overclocked at 4.8GHz, give me 1600KH/s
An old HD7850 give me 2.5MHs (bought used at 90$)
A R9 280X give 5.4MHs
My dual xeon 2687w (each cpu cost 2000$) give me 3.3MHs.. less than a 350$ gpu..
I like cpu mining. But, face it, Q2C is no more a CPU coin. unless you want to waste energy. -with 8 xeons L5530 + 2 xeon 2687 + a 3930K, mining do not cover electricity, or barely (at the current rate), and with the upcoming halving bloc, it wont.
It's sad, but gpu miner change that. I continue to mine with GPUs for a while, but with the vardiff bug/change on the two pools i liked to mine, i go away to mine another coin. (still with Qubit algo by the way)
My CPUs are now on another coin too, trully cpu only - for the moment - coin