Apart from the angle of the CD/DVD. you will need to make sure the disc does not slide, as it's being inserted.
Some CD's used to come with small pull-out tabs that you could trap the disc into, if the CD ROM was being used vertically.
PC's are sold as being able to be used either Horizontal or vertical, so I don't see that tilting it "by any degree" is going to make any difference.
Apart from the CD/DVD mentioned above, there are no other parts that are effected.