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NickB  
#1 Posted : Tuesday, July 15, 2008 3:59:03 PM(UTC)
NickB

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I recently moved my 2006 iMac C2D 2.16 with ATI X1600 256MB VRAM from 10.5.2 to 10.5.4, since then I have been experiencing what I would describe as screen tearing.

UserPostedImage


I am still using CU V4 (that's a long discussion), and am guessing that this is an Open GL issue as a few other people have reported this on the Apple discussions forum, some with games, and another with VectorWorks. My question is has anybody else seen this ?

The tearing always starts while I am using CU, usually when I am panning my model. The model is not complex, but the file is over 50MB with I would guess 200 plus layers. Once the tearing starts it spreads over into all other applications even after I quit CU, but is most evident when dragging a window or other graphics intensive operation. Shutting down and re-starting my Mac is the only cure I have found. The only other time I have seen this sort of screen breakup is when you have several light, and perspective on and try and move a model, but then it is limited to just the model breaking up into triangular shapes, not the whole screen and other applications.
Shark FX 9 build 1143
OS X 9.5
3.6 GHz Core i7, 8GB, GTX 760 2GB

matter.cc
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ttrw  
#2 Posted : Tuesday, July 15, 2008 5:37:08 PM(UTC)
ttrw

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I've never seen or heard of anything like this.

I would imagine that if the problem persists with other applications, then it is your computer that is at fault.

I'd try 4 things first;

1. Repair disc permissions

2. re-seat the memory

3. Reset the PRAM

4. Reinstall OS X

You may have a faulty logic board, but I'm only guessing, iMac's are a pig, because everything is so sealed up.

If all these fail, take the iMac back to Apple and get proper feedback.

Sorry I can't help more.
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Tim Olson  
#3 Posted : Wednesday, July 16, 2008 9:09:40 AM(UTC)
Tim Olson

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>>256MB VRAM duel 20 inch displays

Kinda sounds related to the board & config. What resolution are you running? Does it go away at lower screen resolution or single display?

Tim
Tim Olson
IMSI Design/Encore
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jol  
#4 Posted : Wednesday, July 16, 2008 12:45:02 PM(UTC)
jol

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Not sure .. but Tate Modern would certainly give you money for it !
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ttrw  
#5 Posted : Thursday, July 17, 2008 3:28:55 AM(UTC)
ttrw

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Or if you can animate it, would it be fit for the latest video by Autechre? :cool:

fwiw, My MBP is almost the same spec- but with 128mb VRAM, and I am using two monitors- 15" and 20", and I have no problems.
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NickB  
#6 Posted : Thursday, July 17, 2008 1:58:15 PM(UTC)
NickB

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Tim,
At thousands of colors all sorts of weirdness appear in CU.

UserPostedImage

For normal modeling things are fine, but when I pan, the screen changes color and splits in half. The image on the left is the working model, the image on the right comes from the last model file I was working on. The right hand model file was not open.

If I quit and try and re-start CU in thousands of colors it crashes on startup (crash report emailed to you directly).

Changing the resolution of the display is not a usable option as at anything other than native resolution, the LCD display is too blurry to be usable. I have not attempted using just one display.

Starting in millions then changing to thousands the tearing / blocking still reappeared with dynamic shading set to either phong or gouraud after opening and closing many layers, copying items to new layers and then panning. The tearing always starts while panning. With dynamic shading set to Gouraud it was several hours before the tearing appeared, with Phong it usually starts after 30 - 45 minutes of use.

I reverted to my 10.5.2 backup disk, and everything has returned to normal. No tearing after 8 hours of use, that points to a driver issue and not hardware.

A Google search revealed that the 10.5.3 update that included many graphics bug fixes has had the same effect for many people when using OpenGL intensive applications and some ATI cards.
Shark FX 9 build 1143
OS X 9.5
3.6 GHz Core i7, 8GB, GTX 760 2GB

matter.cc
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ttrw  
#7 Posted : Thursday, July 17, 2008 3:08:05 PM(UTC)
ttrw

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It looks like the graphics card isn't clearing its cache when loading a new model. I haven't got CU4, but if you say that this also affects other applications, then it can't really be CU4's fault either. You say that you haven't disconnected the second monitor yet? I'd try that first and then see what happens. Personally I still think that this is a hardware fault (unlocked by a driver update or something)- and you may have just had a dodgy batch. I also know (from an inside Apple contact, who lives in SF) that the iMac and Macbook range doesn't get as vigorous testing as the MacPro range. You could just have been unlucky. Have you contacted Apple again?
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