As TC said you can place the extra cables between the motherboard mounting plate and the outside panel of your case. That's what I did with mine. To do so I had to connect two slots in the uppermost drive bay to expand the hole so the connectors could fit through.
In this photo you can see all my cables bundled heading into the upper drive bay. You can also see the motherboard power cables coming back out. The other cables you see are coming from below as better seen (and explained) in the next photo:
Once through the newly formed slot I spread the the cables to be hidden out between the motherboard mounting plate and the outer panel of the case and had no bowing of the outer panel.
I was also able to drag some wires down the case then feed them back out to my optical, floppy drive and hard drives as well as my video card and sound card as seen in this photo:
Finally, you can see in this photo, with a little drilling I was able to route my rear fan cable and hide some additional audio cables between the motherboard and outer panel as well:
In the end there's no cabling cluttering the case and none blocking the airflow from my front fans. I didn't do this until after I had completed my build so I had to take the whole computer apart, mod the case slightly to hide the cables and then put the whole thing back together. The entire job took about 3-4 hours.
Whiles it's hard to see here you can make out that there's no bowing of the side panel facing you in this photo. It's the one with all that cable hidden behind it: