Quick Airflow questions.

[1701E]

Was wondering what Optimal Airflow for a system is in CFM for a Mid-range Gamer PC.  Custom built and generates a bit of heat.
I only have 1x 120mm intake and 3x 80mm out-takes, so I want to get optimal airflow.  Right now it idles a little warm.
Current airflow is somewhere around: Intake - 70CFM (All bottom layer)  Outtake - 90CFM (60CFM bottom layer/30CFM top layer) (Unless PSU is supposed to be added in)


I heard the Intake/out-take should be close to matching, but how close?
Is there such a thing as too much Airflow?

[Masherbrum]

I've always lived by the "No more than 50CFM's for negative air pressure."   

I have an X-Cruiser case with two 80's (intake), two 80's exhaust (side and top) and my 92mm ASUS Silent Knight II blowing directly into my 120mm rear case fan (exhaust).

At idle my PC is 22C.   CPU is 28C, cores are 40C.