yo is my logic board fried?

[Francois Barbary]

K well it's 1 30 and i have an early lab tomorrow morning. so ill be 
really brief.
you guys know my cube it's the one with the dam monitors button going 
off spontaneously, and with usb sound problems, and with fw disk 
problems... just now one of my fw ports is completely dead. it's really 
annoying. because i have an ipod and a external fw drive and want to 
buy a burner...

do you think it could be a logic board failure? or even a system 
controller chip (does this g4 have one?)

(oh by the way by usb sound problem i mean that when my speakers cut 
out the headphone jack still works odd eh? ( i thought earlier that it 
could be that lil` amplifier but i think it's usb because it has a 
resetting sound like static or just plugging in a electric gutiar to an 
amp. its extremely annoying, (because i am a hardcore audiophile)

anyway ill post back hopefully tomorrow.
thanks guys. (and girls)
Francois