Haven't seen that one but I have the beeping/crackle sounds through my speakers... faulty PSU I'm told. I've also heard several tales of G5 PSU's frying machines and "burning" up - not reassuring. You can see these posts on Apple's G5 support forum. If you have a G5, you may want to unplug it when your not around - john.
I had the same problem. The video card fixed it , but I also insisted that they replace the logic board as we had mauled it during troubleshooting, resetting the PMU, on-off-on-off-on-off ....... and trying to clear the PMU ......
This is a very widely reported problem but primarily related to bad video memory.
