Sorry, you won't be able to upgrade it. If you do change it out, all you can do is replace it with the same thing. Even with PCI-E cards, normal judgement would say it can be interchangeable, but no- sockets are different and may won't even fit properly into the chassis. With the damage that you'll do, wasted time and money, you might as well buy a new one. Or at least a barebone and swap out the components from your old one.