they used to allow as hand carry on board, even international flights...........i have seen people doing that before........
however, things have changed since 911, and they are more strict regarding hand carry stuffs, you may know you can't carry big tubes of toothpaste for eg..........and also more strict in your hand carry allowance, which is usually between 5-7 kg..........
even notebooks are now under scrutiny, and at one point, forbidden as hand carry, have to check in..........and i know at least one traveller loosing the checked in notebook at transit in klia..........
i advise against bringing heavy desktop computers over.........what you need is a good notebook.........as a desktop replacement..........
you don't need to spend 7k on a 1.5kg slim notebook.............your intention is to use it as a desktop replacement, ie it sits at your table.........permamantly........so buy one of the cheap and heavy notebooks.........cost slightly more than a desktop computer only.........