Having just installed a windowed side-panel I thought I'd better tidy my cabling up.
So, I put my 2 optical drives on the same IDE channel (making one IDE cable redundant), and at the same time removing my floppy drive (what's the point of them nowadays?). This means I'm 2 ribbon cables down and only have 2 more currently in my box. I routed the remaining cables so they were out of the way.
I was surprised to see I'd knocked off 3-4 degrees C during heavy load (SETI) just by making the cabling tidier. It not only runs cooler, but looks great too under the light of my blue LED fan.
FWIW, I've never had much luck with round cables, but with my ribbons out of the way, I'm very happy.