Firewire port won't work on my PowerMac G4

I have a PowerMac G4, AGP model. I connect one external hard drive and one external DVD writer to my computer through the two built-in firewire ports.

However, the computer mount any of my firewire devices on the afternoon (they still working fine on the morning). I had try three way to fix this problem. I did try reinstall the external devices, I did try un-plug every thing include the power of the computer and reconnect them back, and I also reinstall my OSX.

However, all three ways still not fix that problem. Both of my external hard drive and DVD writer have USB port. I did try to connect them with the USB, and they work find.

So my question is does this problem cause to the firewire port or the mother board of the computer (I don't think this problem is cause by my devices because they still work with USB). How can I find out which part cause this problem? And also how can I fix?

Thank you very much.

CanadaRAM said:

Reset the Power Management Unit
http://docs.info.apple.com/article.html?artnum=95037

or

Boot into Open Firmware (Command-Option-O-F)

Type "reset-nvram" at the prompt followed by "reset-all". Restart

Does this wake the ports up?

Click to expand...

No, both ways still won't wake the ports. What should I do next?

Thank you.

no, reset the NRVAM with Command-Option-P-R keys or open to Fireware Command-Option-O-F still won't wake the ports.

Should be the bettery dead? or still something wrong with the logic board? If the problem cause by the logic board, will a firewire PCI card work?

Eidorian said:

Sounds like fried FireWire ports. A PCI card will work just fine.

Click to expand...

Does any kind of PCI card will wrok with PowerMac G4 AGP? or is there any particular PCI card that can work with? Any suggestion?