We have no reason to believe it is. We only know of consciousness in biological systems: wet, meaty, stuff with the accompanying processes.
Computers are nothing like that, so the burden of proof really rests on people who bring this idea up. I'm not saying it is impossible, I'm saying I have no reason to entertain this hypothesis. Just like I have no reason to entertain that spongebob controls the solar system; no one can prove he isn't, but no one cares.