Does Antec 900 v2 blow out so much hot air?

Any electrical device is going to generate heat while it is on. If you have a powerful computer, which I'm guessing you do based on your case selection, it is going to generate a lot of heat.

Having the fans in the case (or any case with proper airflow) keeps all that heat from being trapped inside and overheating your expensive computer components. The downside of this is yes, it can heat up your room.

So, what can you do? (1) don't leave the computer on when you don't need it. (2) look at downclocking and undervolting your components to save energy and generate less heat. (3) treat your room as a giant computer case and put some big fans in the windows to exhaust the hotter air.

If it is really a problem of the hot air being trapped beneath your desk, causing you to feel warm when sitting beside it, you could always construct a duct with cardboard to direct the heat away from you and out the back of the desk. Or just wear shorts.

Nice Gryhyn I think you just about covered it,

to vertical infinity- do you not have air conditioning?
that can also help keep your room cooler

I run an antec 1200 case. I keep a thermometer on my desk. My AC is set as 73 (digital thermometer for the house ac unit). My computer room stays at about 77 idle. If i close the door and work on the computer for a few hours I can steadily watch the temperature climb past 84 in my room. I've found that keeping the door open so some of the hot air will keep the temps around 80 if i'm working on the computer but the room overall is noticeably hotter then the rest of my house.