Which one of these processors would work in my Mac?

Hi all!

I recently acquired an old Power Mac G4 (Mystic). I've upgraded it slightly (more hard drives,  octupled the RAM) and while it runs OS 10.4 well, it's a wee bit slow. Also, I'd like it to run Leopard (I believe it can unofficially run it now, but from what I've heard it would be slower than what it is now).

I've found a few. I know that I can only go for the square/rectangular boards, not the ones that are shaped weirdly.


(Dual 450s)


(Single 733)

What one would work best, and what would actually fit? If the dual fits, I'll get the heatsink to go with it, IF it goes cheap. If not, then it'll be the 755.

(all I really want to know is if my G4 would run either board without exploding.)


Thanks for your help!