Mr Spocko wrote:
...I very strongly disagree with the modern thinking of bottom mounted PSU's. This IMO has a "negative" impact on airflow. A bottom PSU will draw cool air out of the system as it's placed low down (unless the fan is sucking in from the bottom of the case outside) if it's reversed inside the case it simply helps to take cooler air out which is counter productive to overall system temperatures.
You overestimate the role of convection in a PC case that uses fans. A single slow spinning 120mm fan easily counters any rising heat due to convection. Besides, if the intake fan of a bottom PSU is facing up, it could have a role in evacuating heat from the video card(s), which would be fairly close -- within say 5 PCI slot distance, given the 2-3 slots vidcards occupy these days.
In contrast, there is little doubt that the top mounted PSU...- always runs hotter
, as the primary path of heat evacuation is via the case back panel exhaust fan directly below it. The additional heat, in combination with the low fan speed utilized in quiet PSUs, has the potential of shortening PSU life. I have personally seen several quiet PSUs which failed due to heat damage in cases where the PSU was mounted traditionally. Since a bottom mounted PSU is not subject to the heat from the rest of the PC components, it runs cooler, so longevity is improved. - blocks the possibility of a top mounted vent
above the CPU area to increase heat evacuation