Here is my another project how to hide cables:)
My goals were not to destroy desk with screws and make it cheap as possible.
I put one cable canal on the wall, to hide cables that came from other side (electricity and utp).
Step 1: Cable Canal
I used zip ties to attach cable canal on desk.
I suggest you, to use wider cable canal. It would be much easier to hide all cables.
Step 2: Box Under PC
Left side panel is removable. I put magnets to hold it in position and piece of plastic to easily open it.
Step 3: Wiring
I modified power strip and added switch on the front side of the box, so I can turn off all devices.
Step 4: Finish
I'm very happy with result:)