I think maybe you misinterpreted the question.
I take the question to effectively mean "does a PSU fan normally exhaust air". That is "from the power supply fan through the vent holes"--airflow out, rather than in.
You said false/no.
False would be a correct answer if the question had been:
"In a properly designed, properly assembled PC case, air flows in a specific path from the vent holes through the power supply fan"--airflow in, rather than out.
I think maybe you misinterpreted the question.
I thought so too but I asked and he said "vent holes in the case". After all the discission in class thats how I figured it was false. No big deal...all my classes are out of date. Books are always behind.
For best system cooling, you should arrange for the rear case fans (including the one in the PSU) to exhaust more air out than the front fans draw in. The fans should be arranged so that the inlet fans are sited towards the bottom of the case at the front, whereas the exhaust fans should be mounted at the rear of the case towards the top.
Cool air will then enter the system from the front, pass over the HDDs (as these are usually mounted in that vicinity), and be drawn upwards over the motherboard, effectively cooling the components. Any inbalance will be taken care of by air entering the system through the vents in the side panels. The by now warm/hot air will be exhausted out of the case via the rear case fans. This arrangement allows for a ready supply of cool air to flow through the system, and is known as negative-pressure cooling.
You can quickly check the effectiveness of your cooling by holding your hand near the exhaust fans. With good cooling, the exhausted air will feel slightly warm (mine is cool), but not overly so. If it is hot, on the other hand, you might need to check that the cooling system is working correctly. Check that the fans are correctly orientated and that they are clean and free of dust. Filters are available to trap dust particles. Check that the case vents are clear (for this reason I do not recommend the use of case noise-dampening material that may block these vents). Also check the cabling arrangement on the motherboard so that it doesn't impede air flow.
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