But the cables are so short coming out of the hole. They barely reach. Cables such as the main power cable for the motherboard, and the secondary power cable, etc. The modular bits are actually long enough.
If you have an electric drill and 1/8" drill bit you can drill a series or holes the size of the fan so it can draw air in from the bottom. This would be the easiest way and you wouldn't have to cut out a hole , you could then even place a filter screen over the holes to catch some of the air particles and that way dust wouldn't accumulate inside the case and psu. This may sound hard to you if your not the handy type but this is actually pretty easy if you think about it , just try to draw a circle on the bottom of the case that wiuld line up with the fan in the psu.
Just don't do any drilling with the psu in the case , I thought I'd mention it just in case.