Cabinet Cooling with my PC

[Jswee1]

I've got a HP-110-414 the system is negative pressure with one fan blowing out on the bottom back and some open vents on the left side id like to put a fan in the left corner of the cabinet a USB powered fan like this 90mm but if so what negative or positive air system since air intake on the PC is on the left and output in the back and i can't put a fan on the right side of the cabinet because there is another cabinet next to it. Diagram I can also move the PC from side to side of the cabinet to a just air flow also. If you guys could give me suggestions id appreciate it positive/negative and location of the fan Thanks

 

[CountMike]

Don't worry about positive/negative pressure, it has no much influence in cooling capabilities, it's more about dust accumulation.