[Tweakhead]

I was not suggesting you leave SCSI behind Jules, simply to test to see if removing the cards makes your video symptoms disappear. SCSI drives still kick the ass of anything else when it comes to zooming in/out on waveforms rapidly and dealing with very high edit density.

One of my Pro Tools systems is an old Dual 867 with a Mix++ and a Magma Expansion Chassis. I have all the Pro Tools cards in the chassis and the SCSI card in the mac. It works fine now, but when the cards were in the G4 I had the exact same symptoms you describe. This was years ago I had to deal with this, and it has been fine ever since.

Just work thru the problem logically. If removing all the cards except the host adapter works, then add them back until it fails. Once you know the culprit, then you can deal with the problem.

Is it the stock video card that came with the G4?

Is the SCSI card a UL3D?

I would for sure recommend USB MIDI. I use a basic little Edirol unit, and it works perfectly.