Originally Posted by
Often1
There's no such thing as a standard roll-a-board. They run the gamut from tiny to very large. What counts are the measurements of your specific roll-a-board (remember to include handles, wheels and the like).
Also there's no such thing as a standard sized desktop tower either, so the specific combination of computer and carry-on is going to matter.
I have in fact transported desktop mini-towers about 2-3 times, both in carry-on and tightly packed in check luggage. All have been fine, though one got a dent in the side of the case. I do feel anything bigger than a small mini-tower is going to be very tight to fit in a typical carry-on. I have also transported 20" LCD monitors in my carry-on twice as well.
As long as it fits, there's no real issue, though the security line does give some funny looks and may give these things an extra manual look-over.