Just a quick note:
I’ve bought one of these desks: an Ikea Fredde. They are great, quite sturdy.
But while on the IKEA site there is info regarding the outer dimensions of the desk, there is almost no info regarding the size of the bottom shelfs. So for helping you out there, these are the dimensions of those shelfs:
Height on the point it meets the under the bar supporting the desk table: 47cm. Otherwise height 50cm.
So if thinking to put a large computer on one of those shelfs, forget it. I have a Cooler Master CM690 case, and it doesn’t fit. There isn’t enough space in depth and height and also no space at the back for the cables. A much smaller computer case will fit fine, if, at most, the depth size doesn’t exceed 40/43cm and it’s height is under 46cm.