How important are intake fans?

Case ventilation, airflow, and cooling are very important for gamers and enthusiasts. The combination of intake and exhaust fans help to cool internal components, especially the cpu and video card.

Here is a link to a web page with an animation depicting the classic bottom front to top rear air flow. Scroll down to the bottom of the page to see the animation:

http://www.lancoolpc.com/en/product/product06.php?pr_in...

So it is best to buy a high quality chassis with the option to add a front intake fan?

more exhaust air flow is always more important than intake. a fan at the upper rear getting the hot air out is most important, and as it removes this hot air, cool air is also drawn in through ventilation holes in the case. I have tested this using 1 fan. temperature is much lower when it is set up at the upper rear sucking out hot air than in the front blowing cool air in.

but i see that some chassis dont have holes in the front like this?does this have the optional front intake fan?
http://www.360buy.com/product/238168.html

i dont have a rigid budget but i am asking did the previous chassis have a front intake fan?

we can?how can we do that?

thanks..if you do have a link on how to install a front intake fan.please pm me.

Best answer selected by zulfadhli.