I've got 2 sets, 2x4-inch and 2x12-inch, CCFL UVs. I try to position them to light my tubes from as many directions as possible. 1 12-tube is along the back left, the other is zip-tied right of my mb. 1 4-inch is positioned with velcro to the bottom back of my PSU the other is velcro'd to the top of my case in between my rad and res, mostly to light up the res. Of course your situation is going to be different in many ways, but the principle is the same.