[mtro]

Hello All
After years of faithful service, my G4 400 AGP has been suffering a series of calamities which has culmininated in a worrying crash leaving thin vertical coloured stripes on the monitor screen. Sometimes the pattern is disrupted by a regular pulsing of about 1 flash per second. The stripes are usually green and magenta on a black background but have also been red or blue. Sometimes a faint noise is briefly audibile from inside the machine at the moment of the freeze.
The crash occurs every time I start up the machine, and occurs during the boot process or within the first 5 minutes of use.
Here is my machine spec.:
G4 400 AGP
Sonnet Duet 2 x 1.3 GHz processor upgrade
1024 MB RAM
Ati Radeon 8500
Acard 6820 ATA controller
3 hard drives / total 240 Gig
Pioneer 108 DVD+-R
Max OS 10.3.7 / 9.2.2
History:
I installed the Sonnet upgrade early November and was delighted with the result. For 5 weeks the machine ran lightning fast and smoothly.
About 10 days ago the Sonnet Processor burned out. The power supply also went. It was a bad day....
Yesterday I received a brand new replacement processor card and a new power supply unit (apple compatible). Installation was, as ever, simple.
The machine started immediately, and can boot from any drive (6 partitions) into either OS 9 or Panther. However, very soon it began to exhibit the behaviour described above.
I have no idea which component is at fault, and I do not have the time to experiment at the moment...
I have never come across this sort of crash before, so I would be very grateful if anyone could offer advice.
Thanks
Michael

[almaink]

I'd check the video card.

[mtro]

I took out the new processor last night & rebooted with the original G4/400 instead.
Guess what. No problems at all... it's just much slower again :-(
That makes two dud 650 Duets from Sonnet in a row. A cautionary tale for all those considering the upgrade.