I've seen several builds on this website. So... my question is.. Are the PSU fans supposed to be facing up or down?
Down, usually. It intakes air, so it should take air from outside rather than inside.
Depends on your PSU. My PSU has an option to not turn the fan on unless it's pulling more the 350W, which it rarely is. So for me, I have it facing up. Most people prefer down though. Also prevents screw from dropping into it through the fan grille.
okay, I have a AX760 and a AX860 Corsair. I guess they are designed to do either facing up or down by the way they placed the stickers on the sides.
On a bottom mounted case, the AX760 and AX860 should have the fan facing down, and the sticker should be the right side up.