Q: NVDA(OpenGL): Channel exception!

I have had these same issues for going on a year now (since 10.4). I have tried all of the fixes mentioned here, but none have gotten rid of the problem. SMCfancontrol made it better for a while, but it's still gotten progressively worse over time.

I've heard many theories as to the exact cause of this issue, from the driver using > 2GB memory area (I have 3GB), to heat problems (which don't really make sense to me, since a simple reboot will make the problem go away for a period of time, though this doesn't cool off the machine) to driver code issues (could be related to the high memory).

Whatever the cause, I could wait no longer for Apple to provide a fix. It seemed to me that this specific issue only happened with the Geforce 7300 GT card. It's possible that card is just so much more prevalent that it's generally reported that way, though.

As a result, I recently replaced my Geforce 7300 GT card with a Geforce 7600 GT, and am happy to say I've not had an issue since doing so four days ago, knock on wood. I bought the card for $231 and replaced it myself. I'll post here again if the problem comes back.

OK, I have the same issue. Reverted back to 10.5.6 and since 5 days no problem. I wonder if it is fixed in 10.5.8

I hoped this gets fixed in 10.5.8., made the upgrade, but NOOOO, the failure still persists.
Before I start the 3D Applications in question, I make "shutdown -r +3", so if it crashes (what it does every time), my mac will reboot 3 minutes later.

i understand the Video card is seperate from motherboard on these versions. Any recommendations as to whether a novice could make the change ie me, or has to be taken in. Plus recomendations for replacing the NVIDIA GeForce 7300 GT card

Well....

I started getting these problems two weeks ago.

Everything was perfect and suddenly it hung, frooze.. spinning beach ball. I'm sure it happened after an update.. but in all honesty I don';t keep tabs on them.. just restart and updates crack on.

So.. after numerous hard restarts... (every couple of mins) I archive and Reinstalled back to 10.5. I have a NVidia 7600GT (?)

The hard restarts have stopped but it still freezes for a good minute or so and frequently the screen gets pixallated and messed up.
I've tried 10.5 10.5.6 and most up to date 10.5.8 and they all have issues as described above.
Have removed software that I think might conflict and still the same....

I'm really starting to think its a hardware issue and the graphics card has had it.
So I'm buying a new one.

This is all due to faulty Nvidia Chipsets. This problem got acknowledged by apple and nvidia for the notebook chipsets. But a lot of industry sources claim, there are a lot more nvidia lines that are affected. I guess the 7300GT and the 7600GT are one of them. It just took about 3 years of usage and material fatigue to show up everywhere. I am glad to have AppleCare since they are going to exchange my 7600GT for free now. I let you guys know if it helped.

What are we iMac24"-ers to do? Apple?
In the iMacs, the video-boards cannot be exchanged, can they?
I still have a MONTH of Apple Care - OUCH!
Apple should get reimbursed by Nvidia, a assume.

In a 24" iMac, yes, the video card can be replaced. I replaced mine 2 weeks ago, and no problems since.

Happy me!
They took out the old one, and replaced with which card?
I am calling Apple Care!

Here is my documentation of the process of replacing my video card in my 24" iMac:

http://sap-dba.blogspot.com/2009/08/replacing-video-card-in-late-2006-24.html

And the Nvidia Geforce 7600GT gave you no more issues?

Nope. It's been error free ever since.

I had my 7600GT replaced with a new one today. ROM-Version changed from 3021 to 3022. But unlike I hoped, nothing changed. I still have the following error which crashes my GUI:

+imac kernel[0]: NVDA(OpenGL): Channel exception! status = 0xffff info32 = 0x3 = Fifo: Unknown Method Error+

@al_broccoli: could you please download the Multiwinia Demo at http://www.introversion.co.uk/multiwinia/downloads/ and test it on your mac. This one crashes my GUI for sure everytime. Introversion told me, it is a bug apple is aware of.

Guys... this is kindo strange:
- had a 7300GT installed due to the problems in this thread, was on 10.4.7
- with this new one installed, had same problems
- downgraded to 10.5.6 - no problems visible (10.5.6 with Safari 3)
- found this thread, thought it was a card issue, and expected to have to go get card replacement again, possibly to a 7600GT
- BUT: Apple suggested i upgrade to 10.4.8, in case that would work, instead of getting new card
- And it did! NO problems with 7300GT (rom revision 3022)

Whacky, eh?

What an ordeal!! I've been experiencing increasingly difficult and changing circumstances for about 3 months. Everything that has been reported here I've experienced. I've followed this thread and tried every suggestion. I tried booting from an external drive and went back to 10.4.11. I ran every utility and diagnostic including hardware test and everything always came back as passing. The ordeal ended when I got an ATI Radeon HD 3870 video card. Problem solved instantly!! Sorry NVIDIA I'm a little gun shy of your products now.

When I purchased my Mac Pro DP 2.66 Core Duo machine I didn't pay attention to the fact that one video card would run both my displays so I ordered 2 of these NVIDIA GeForce 7300 GT cards...AND THEY BOTH WENT BAD!!! I tried every combination of one card or the other or both in every port and they're both no good.

I really like this new card, I popped it in WITHOUT running the software first because the machine would no longer boot. Also, I had brought the OS back from 10.5.7 to 10.4.11 which is not recommended for this card. The card needs 10.5.2 or higher. I also did NOT connect the power cable to the motherboard. I popped this card in and it ran. All problems solved instantly, the machine booted right up and ran. I did connect the power cable and then did update the OS and installed the video drivers. What an ordeal!