[direinsanity]

If i bought a g4 power mac like a single 500mhz or so I found a site where you can buy 1ghz g4's for power mac for around $200, could I buy an older g4 and put the newer chip in it? would this idea work?

[Zoom]

I had a G4/400 Sawtooth and put a G4/800 upgrade CPU in it (overclocked to 900Mhz). Worked great.

The web site should have something about compatibility on it. What's the link to the upgrade and what specific G4 model do you have? Need more details. But surely the upgrade web page has info on this. If not, call the manufacturer.

[ReggieX]

Short answer: no.
True upgrade cards cost more.

[Lateralus]

Here is a list of upgrades that will work in a 500MHz G4.