Fans for Dell XPS 8300

[reqhjack24]

hey guys. I've gotten into overclocking lately (not raising the voltage though).
i heard that my PC performs faster when it's cooler, so i decided to get some fans.
my case is unfortunately Dell XPS 8300. i just switched out the GPU and the PSU.
so apparently, airflow is horrible with all the cords.

here are the dimensions...
Height: 16.02 inches (407.75 mm)
Width: 7.31 inches (185.81 mm)
Depth: 17.9 inches (454.67 mm)

I'm definitely getting a PCI fan to cool my gpu and to blow out air but could i also get a front fan?
theres a little space on the bottom in the front but i dont know what size would fit. also i dont know
if i can even screw the fan onto the case. please help!

 

[JKatwyopc]

Measure the size of the opening with a metric ruler and then get a fan of that size. standard fan openings are (almost always) 80mm, 100mm, 120mm, 140mm, 200mm, 220mm, or 240mm. Most likely yours is either 80mm or 120mm.

For good airflow you should have one intake at the lower front and one output at the upper rear of the case minimum. Often the PSU fan acts as the output fan especially on OEM style cases.