A quality PSU is a wonderful value when it has a 10+ year replacement warranty and provides optimum clean power to all of the components extending their life vs. a low quality PSU with dirty power.
Intel designed the ATX cases with the PSU at the top of the case because heat rises and the PSU fan can easily extract it. Any quality PSU is not compromised by the typical heat generated in a PC. A quality PSU is a wonderful value when it has a 10+ year replacement warranty and provides optimum clean power to all of the components extending their life vs. a low quality PSU with dirty power.