It depends, but that is rather weird.
On most power supplys now, there are two fans. One above inside the case which pulls air in and then one outside the case behind it, which pushes the hot air out from both the power supply, and internal case.
If there is only one fan on his, and its pushing cold air into the power supply, this is okay I guess, but as a result, thermal temperatures inside the case will get higher, where the video card usually lies if its a bottom mounted one.
If its a top mounted one, and there is an exaust close by, it shouldn't be a problem.