PC. Motherboard Fan

The fan on my MOBO is going to die. It is an ASUS Mobo and there is a small fan over the main chip. To remove it means a total dismantle of the MOBO and then snip the pins on this fan from the back. I just don’t fancy doing that to my 5 year old PC, which I’ve upgraded with more HD (1TB) and more memory (4GB).
It’s going to die because I was getting warnings about Chip fan speed from the bios boot up screen.
I cleaned it with brush, blower, sucker etc. etc. It is Ok now and seems to be maintaining speed ( I downed “Speedfan” so I could watch it.).
But it will die in the end.
So, I was going to buy an ordinary 3 inch fan and just add it to the case, blowing on the Mobo. (With a suitable inlet of course). I’m doubling up for the time being but that shouldn’t do harm should it? Can’t really have too much cooling can you? Also, where should I take the power from for such a set up?
Oh, btw, I’ve been in touch with ASUS, because they were replacing this fan FOC for Mobo’s made 2006. They politely told me it was too far out of warranty, and that they didn’t make that mobo/fan anymore so there was actually nothing he could replace it with. Another reason why I don’t want to take the old one off.