Date: Sun, 4 Jan 2004 12:43:27 -0600 From: Jeff Walther <[EMAIL PROTECTED]> Subject: Re: 64MB Radeon & PowerLogix 900 MHz CPU
I have seen a similar problem with the 64 MB cards (from Sapphire, haven't tried the PowerColor) in a Beige G3 with the stock G3/300 ZIF installed. It's weird. The start-up screen is okay, but when it gets a little bit into the Welcome to Mac screen and the progress bar creeps a little, then the screen goes to horizontal hash.
On my Radius IntelliColor Display/20e the display just comes out of sleep mode for a moment and then ducks back in. I thought my Viewsonic 6e worked okay with no problems, but yesterday I had a similar problem with it. Dropping back to OS 8.6 made the problem go away. Starting without extensions also solved the problem under OS 9.1 (with OpenGL 1.2.4 installed).
Dropping back to the 1.19 ROM also solves the problem.
Okay, I did some more investigation into this problem last night and I have a theory. However, I cannot explain why this problem arises with the flashed 64 MB card and not with the original 32 MB card. It might be interesting to get a flashed 32 MB card to test it on as well.
Anyway, I believe the problem is caused by sloppy support for older monitors and not by any video RAM or timing problems. This would also mean that the problem is probably machine independent and completely dependent on what monitor and/or cable you're using with the card.
In my case, with the V 6e, for some reason the card was reverting to a 1152 X 870 @ 85 Hz resolution which is way outside what the Viewsonic 6e supports, thus causing the hash. Even after setting it to a supported resolution and other things like resetting the CUDA and zapping PRAM, trashing the Monitors Preferences, the card will still jump to that resolution under some circumstances.
Once I've got it set to the resolution I want and if I don't change which monitors are plugged in where, it will stay set. But rearrange a few things and it seems to default back to an overly challenging resolution.
Note, that it does not start up in the high resolution. It switches to it after some extensions have loaded.
So that solves the Viewsonic 6e mystery.
In the case of the Intellicolor 20e, I believe that the R7000 is just deciding that there is no monitor attached and shutting down that output. If, after booting, I remove the Intellicolor's cable from the R7000 and connect a different monitor in that spot, there is no signal. So the R7000 is not outputting signal to the port to which the Intellicolor was connected.
As I mentioned in my previous message, if I insert a VGA-Mac and a Mac-VGA adapter between the R7000 and the Intellicolor, then it works properly. The Intellicolor has a removable cable, and installing a cable from a NEC monitor also solves the issue.
Okay, the final bit of information. As far as I can tell, the big change from revision 1.19 to revision 2.08 of the firmware was to add support for DDC (Display Data Channel) which I gather is a newish feature in VGA monitors which does something like what Apple's sense codes in their monitors did fifteen-twenty years ago.
So if the new firmware is causing the R7000 to read this DDC information off of the monitor cable, and sometimes it's getting a spurious signal from an older monitor, that could cause the R7000 to either think that there is no monitor present (Intellicolor 20e) or that the monitor present is best used at a much higher resolution than it actually supports (V 6e).
This would also explain why dropping back to revision 1.19 of the firmware solves the problem. If you ditch the DDC support you lose the mis-reading of the attached monitor problem.
I do not understand why this would work any differently for a 64 MB flashed card and a 32 MB original ATI card, though. That is the unexplained hole in my theory.
It would be interesting to read what make and model of monitor the original poster was using and what it's top supported resolution and refresh frequency is.
Jeff Walther
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