Yeah, its very bizzare that your motherboard is hotter than your CPU, and to me, thats rather worrying, even though you do have fans on it.
Plus your CPU's rather hot if its idle, and the CPU fan is running over 4000 RPM... hmm strange... but the heat has no where to escape.
You need a fan at the back, I think to draw the hot air out of the machine, and if you have a space at the front for a bigger fan, draw cold air in from that.
So then you have a cold flow coming in and a hot flow coming out. That is when the side won't make much difference, and you won't have to worry about the cat