If there is a door on this shelf leave it open and test.
Remove the side panel from the pc and test.
My Acer Aspire XC-780 (Intel i5 - 6400 quad core processor @ 2.70GHz and 8 GB ram) is 2 years old, has low build up of dust inside and works fine.
It is currently very hot where I live and room temperatures reach up to 30 degrees Celsius. My desktop computer can get very hot during these times.
My computer is located inside a desk shelf. The computer fits nicely in their with plenty of space to the computer's right where the CPU fan blows out hot air. I am not sure if the power supply has a fan but if it does, there is a 5cm gap from behind the PC and the wall.
My CPU reaches 60 degrees Celsius when playing a low demanding game for about 10 - 20 minutes. When watching streaming movies or watching videos my CPU is at 45 degrees Celsius and when idle it is at 40 degrees. My motherboard gets minus 5 degrees than the CPU for each activity. Is this good or bad?
My question is how can I keep my computer cool during the summer months and also can I use a USB desk fan (4 inches) to cool down my computer in anyway? If so what position.