Q: NVDA(OpenGL): Channel exception!

Alright, so 10.5.6 it is.

Now, pardon my dumb question, but once I downgrade to stock Leopard (10.5.1?) how can I stop the software update process so that it does NOT go beyond 10.5.6 ?

Thanks much!

I don't expect you'll have any luck downgrading. Many have reported the same issues on all versions of Leopard and Snow Leopard.

No it does work. Downgrading to 10.5.6 FIXED my problem completely.

jfmori wrote:
No it does work. Downgrading to 10.5.6 FIXED my problem completely.

And yet it didn't do anything for others, so you can't say it will work for everyone. Perhaps your problem is different? My problems (system log errors and visual problems) have occurred since long before 10.5.6, so I don't expect it would be a "fix" for me.

jfmori wrote:
No it does work. Downgrading to 10.5.6 FIXED my problem completely.

You also have a Mac Pro, whereas I, and the other poster, have iMacs. Can't guarantee the same "fix" will work for different machines.

This issue is quite tricky...

But just for the record. The day that I upgraded from 10.5.6 to 10.5.7 this is when problem started to happen with my video card. It took about 3 visit to the Apple store. They changed all my RAM, changed the Motherboard, changed my video cars. Nothing fixed my problems until I decided to revert to 10.5.6.

That's what fixed the problems for good. So I believe that in my case and many others, that the problem is coming from a hidden video card driver update inside the 10.5.7 OS update.

All of my 3D applications are not working under 10.5.7 and up, but are working fine under 10.5.6 and below.

When using such software I will get a BBOD every single time.

Hope it help

Interesting. Were you getting the NVDA OpenGL Channel Exception error message in your system log?

For what it's worth, I was having multiple hangs daily up until Snow Leopard. 10.6 seems to have fixed everything for me, as I haven't had a single crash or NVDA error since then.

I'm extremely pleased as I was beginning to think I'd only remedy this with a new Mac.

Strange.
I was having the channel exceptions on 10.5.7 and 10.5.8 and had reverted back to 10.5.6 without any problems. After reverting the imac was operating quite fine for several months with no graphics glitches in console etc.

Now 3 days ago I took a leap and installed the 10.5.8 combo update, as i would like to move to SL once stabilised -though not if there are still graphics issues.

So guess what for 3 days now, no graphics glitches (now I have written this it might change (:-)) ). So went from 10.5.6 to 10.5.8. Therefore there might be something in 10.5.7 which is causing the issue.

STRANGE - will stay here for sometime to see if stable then leap to SL.

hey! woud recomnd. u to contact apple support

I have a late-2006 24" iMac with the nVidia 7300GT GPU. I began experiencing the "glitches" (horizontal lines, system freezes requiring hard reboot, etc). after installing 10.5.7. I didn't install 10.5.8 but reverted back to 10.5.6 - no difficulties whatsoever. I picked up and installed Snow Leopard earlier today and so far (keeping fingers crossed) no problems.

Hopefully it was just a wonky GPU driver and the issue has been resolved ...

I also confirm 10.5.6 was stable.

I've the same problem on my mac mini (latest version) after upgrading my new snow leopard from 10.6 to 10.6.1, 2 days ago (11/9...). When the screensaver start (i use random screensaver), sometimes the mac freeze. Only the console is blocked, because telnet to mac is ok and all other process are running. Shutdown from command line daes not complete and to reboot i need to turn off power.

After reboot, in file /var/log/kernel.log i see these lines:

----------
Sep 12 14:11:46 lego kernel[0]: NVDA(OpenGL): Channel exception! exception type = 0xd = GR: SW Notify Error
Sep 12 14:11:47 lego kernel[0]: NVDA(OpenGL): Channel exception! exception type = 0xd = GR: SW Notify Error
Sep 13 21:28:54 lego kernel[0]: NVDA(OpenGL): Channel exception! exception type = 0xd = GR: SW Notify Error
----------

After upgrade to 10.6.1 on 11/9, i had 2 frees: 1 yesterday 12/9 and one 30 minutes ago, 13/9.

I use this system from 4/2009 and never i had this error, using Leopard 10.5.x and also with Snow Leopard 10.6. With 10.6.1 i had 2 freeze in 2 days !!
The problema *is 10.6.1*.

How can i downgrade from 10.6.1 to 10.6 ??

Thanks a lot.
Vincenzo Belloli.

I have been reading the "iMac Freesing" thread for some time: http://discussions.apple.com/thread.jspa?threadID=2136365&start=0&tstart=0
and I do have these problems with my late 2006 iMac 24". But if I read this thread it looks familiar too!

Could anyone tell us how to make sure how to distinguish these two problems? The iMac Freesing problem seem to very hardware-based and without real solution. The other could be software-based because and I do see some driver updates os system downgrades that give permanent relieve. (Is't it?)

Hi,

Here is my experience. Since 10.5.7 update, my late 2006 imac with 7300 GT graphic card is freezing several times a day. As I'm getting upset with this problem I did some tests yesterday.

1 - Backup off my box with time machine
2 - Format my 500 Go HD and installed 10.5.1 with original DVD
3 - Update system to 10.5.6 with combo update

*NO additional software installed. NO data migration from time machine.*

=> Used the computer for a day *WITHOUT ANY* freeze (safari, itunes, quicktime ...)

_Sounds like 10.5.6 is OK._

Now second test:

1 - Format my 500 Go HD and installed 10.5.1 with original DVD
2 - Update system to 10.5.7 with combo update

*NO additional software installed. NO data migration from time machine.*

=> *Used the computer for an hour and sudden freeze using safari*.

_Sounds like 10.5.7 is KO._

Now third test:

1 - Format my 500 Go HD and installed 10.5.1 with original DVD
2 - Update system to 10.5.8 with combo update

*NO additional software installed. NO data migration from time machine.*

=> *Used the computer for 15 minutes and sudden freeze using itunes*.

_Sounds like 10.5.8 is KO._

Now last test:

1 - Format my 500 Go HD and installed fedora core 11
2 - Compiled a kernel while playing a 3D game

=> *Used the computer for 2 hours without any problem*.

Conclusion:

1 - This is not a hardware problem
2 - This problem is not present in 10.5.6
3 - Problems start with 10.5.7
4 - Problems are not fixed in 10.5.8
5 - This is a problem with nvidia driver and opengl

Regards