alright i got this,
first, consider this, your parents might now let you get a pc because they are trying to teach you to save money , or that they think it is a waste of money, before you go destroying your pc, you could try telling them how important it is to you (if indeed it is that important), or you could just go and buy one if you do have all this so called money, even though your parents wont allow it do it anyways and that way ull get a new pc and only get into a little bit of trouble. Now if you dont care what your doing to your parents or your parents checkbooks, then do one of these things
i got a little creative)
1.) poor motor oil all over your mobo while your pc is running (noticeable thouh but ver fun)
2.) unplug your hdd and psu
3.)go into your windows files (assuming your running windows) and just start deleting everything you have
4.)take your pc out in the back yard and have you and 2 friends beat the living @#$% out of it (like on office space on the pc was replaced by a printer)(very noticeable)
o.k. seriously now
just unplug various things, if you have a sodering iron get creative, but please do think about your parents when you do this. btw im only 14 and saving up 700 dolla 4 a new pc. If i can do it you can to, and im not mooching off of my parents, its called work my friend.