I am not familiar with A1200 tower kits. So, my answer will relate to generic towers. (But I do have an A4000 in a Power Tower).
The front panel should contain a grill. It may look like louvers, but it allows "air" into the cabinet. Airflow is based on CFM.
Anytime you increase the "outflow CFM", you need to either (1) increase the space between the louvers, or (2) add an "inflow CFM" fan. Maximum effect dictates that "inflow" be as far away from the "outflow" as possible.
From your description, the power supply is at rhe bottom of the case, and vents internally into the tower. The flow is upward. If you have a expansion slot just above the power supply (and enough room), I would suggest a blower style fan. The ($17) Antec Cyclone 77094-1 will provide 22 CFM at 28 db noise (3yr warr). If you want more power, the ($10) Alpha/Omega FC2000-B provides 42 CFM at 30 db noise (5 yr warr).
There are fans that install into any unused drive bay, replacing the cover plate that can improve the "inflow". The better styles come with filter material that can be cleaned or replaced.
I have drives that were run 24/7/365 for over 7 years, without failure. These drives operated at 85-115F. The saving grace was forced ventilation at over 60 CFM.
