PowerMac G4 video card security

Hi,

I have a PowerMac G4 with a broken video card i think.

I have a Radeon 9200 SE video card more and i tried to run with this one.

The originaly video card of the PM G4 is an Radeon 9000 Pro.

When I pushed the power button on the computer, nothing happened...!

-With the broken one >> No video but the computer goes on,

-With the other one >> Nothing...

So, I just take a better look on the bus, and on the Radeon 9000 (originaly), there is a little part more just next to the AGP port. And no on the Radeon 9200 SE...

So, maybe it's a security or do you think there is no link betwin the "no power on" and the "little parts"??

Thank a lot!