Can case PSU vent have negative long term affect on PSU

Hello everyone, I have a question. I'm using the Lexa S case and I was wondering if the the vent at the bottom of the case could possibly have a negative long term effect on the PSU. The vent is pretty narrow and doesn't fully expose the fan. Right now I have the PSU facing upwards, but I want to know if facing the fan downwards could possibly cause A: higher temps and B: shorter PSU life span. HX650 is my PSU. The vent looks like this http://ift.tt/1lQGajW