Dr. Zeev Hed could advise us using his lab experience
when electronic parts that generate their own heat
must not be allowed to reach the high temperatures
possible by their own usage, or being near other hot areas.
The complex science and math associated with this area
that explains the dynamics of colliding objects for sure
gives Zeev common sense insights the rest of us can miss.
... temp is now [too high]
... need a bigger fan?
... or mount [another] fan in the case [to] draw fresh air in
renshen1,
Your computer is located in a warm spot of the house.
Rather than
"draw more fresh air into pc box, using an additional pc fan"
I would comment that the air external to the pc box
is not "fresh" but stagnant and at a higher temperature
than the other parts of this room. If so, then a simple
quiet room fan pushing the heated air above the computer
will create that "fresh air" of a lower temperature desired
outside the pc box, and the current pc fan may be enough.
A room fan to exit the room air into another room can help
if the joining room is less warm.
D:oug