Optical drive
Laser pointer because they both use lasers
eyes because see
fire because they both "burn" things (burn as in write files through the powerful high heat temperature)

Expansion slots
hole because they are both openings
a piece of a puzzle because they both fit with another piece to form a bigger thing (a puzzle piece fits with another to form the bigger picture, while the expansion boards can be fit to the expansion slots to upgrade the PC
An empty space in a painting because you can add more to that space to improve the object

Cable Ribbon 
A catwalk because they both connect objects/areas
a fettucini noodle because their shapes are both a flat elongated stretched rectangle
a set of colored pencils, comprised of parallel items (the box is full of pencils parallel to one another while a ribbon cable has many parallel wires in it)