How close to wall can main case input fan be?

[celegansium]

I have a system built in a Rosewill Thor V2 case, which has a 230mm input fan in the left side panel. I have to rearrange the room, and the only place to put the computer is with the left panel parallel to a wall and fairly close to it. I'm wondering how near the wall I can put the machine without causing airflow problems.

My plan was to note the fan speed (from motherboard BIOS) when the machine is far away from the wall, then move it closer bit by bit until the fan slows
down. Then back off a couple of inches for safety. Think that's good enough?

One of my concerns: the left side panel has a lot of screening in addition to the fan, and I don't want the fan sucking warm air out of the case through that
screening, then pushing it back in. Same with exhaust air from bottom-mounted power supply. (Or air from the top rear case exhaust fan, for that matter.)

[Acebmxer]

Moving the system against the wall wont stop the fan from spinning as it is a electric motor. Only thing can stop it is physical object is the fan blades direct path or lose of power.

As for air flow issues it would be best if you could leave 2 - 4 inches between the system and the wall.

[casecutter]

It will also get alot noisier if it is stuggling to get any airflow over the blades. You'll get turbulence. 2-4 inches is a good safe minimum as stated.