Hi,

I built a PC. It has not very high specifications. I used the i5 6600k CPU and 8GB RAM with 500 GB Storage. I assembly is mounted in a rack case custom built by metal case fabricators. I chose that because I need to keep it over a server rack in my office. After installation, I found that system is overheating.  It appears not to be the problem with motherboard or CPU cooler. The size of the case is 3U and used an 80mm cooler master fan.

Do you think the case is small or the fan not powerful enough for air intake? There is 60 mm distance between the server rack and the PC case. Apparently, I can't move the system anywhere else.

Thanks for your time.