OSX Lion, Graphic Artifacts

Hi all,

I realise this topic is dated but hopefully it'll help someone out there with a 5750 still kicking around.

Found this thread after helpful advice from Andrew Humphreys as I've had artifacting issues with my Mid-2010 27" iMac for quite a while.

The first time the problem occured, the 5750 was replaced under Apple Care. I also had a hard-drive nearly die but luckily caught it in time because Apple run their devices way too hot. After the replacement GPU (and hard-drive), I installed iStat and cranked up the minimum fan speed to keep things cool.

Fast forward a few more years and artifacting is getting worse but, like most of you, mainly during the cooler months which made me think it was drivers and not heat. Unfortunately there was no real way to easily stress the system to prevent lockups (they'd happen frequently and sometimes with minimal artifacting) so I researched on modding the GPU to prevent it downclocking or undervolting.

I had recently swapped out my 2TB WD Black for a 1TB Samsung 850 EVO SSD (after moving to a NAS for media and backups) and was determined to get a few more years out of the Mac so cleaned up the heatsinks and reapplied thermal paste to both the GPU and CPU.

But Winter came and nope, still no good so found the details for flashing the BIOS to either run a higher stock clock speed or overvolt. After loading the stock BIOS, I figured out it must've just been due to the drivers using the wrong profile so set all 4 profiles to 700Mhz on core, 1000Mhz on RAM and 1v on die.

Unfortunately it took a bit of time to do all this as I had to load W10 onto a new partition but rebooted and no more artifacts.

Let's see how long this lasts!

is your backgroud set to "tile"?

there was a post earlier mentionning tiled desktop images. your artifacts are on the background and dockshadows. You should try changing it as a first step. just in case.

Those artifacts are graphic card related. There was an issue with SnowLeopard and some 2009 iMacs. Keep checking the forums. if you see a lot of complaints, Apple will be working to fix the driver issue. If no one is complaining, I'd say your card may be flaky.

formatting won't fix it.

Screenshot: http://cl.ly/8kkr

Happens to me too. Quite random for the most part, but the last few times it happened was during HD video playback (on Quicktime, vimeo/youtube).

It would start out as random flickering of artifacts on the video then suddently the entire screen would get affected.

Mid 2011 iMac 27", i7 6970m 1gb

I'm getting this artifacting as well. It's completely random. I'm on a Late 2006 20 inch iMac

Hello,

My 2008 Intel iMac (under Lion) was working perfectly until last night.

So yesterday night, the screensaver appeared (it's the one with Nature pictures), like it does usually.

After a few seconds I noticied that every picture was followed by a kind of "white flash". This was really frightening.

So I moved my Magic Trackpad in order to go back to the Desktop.

And then, artifacts appeared on the top right corner of the screen, "printed" into the desktop background.

I rebooted immediately and haven't to face this issue anymore yet, but I feel like I can't rely on my iMac anymore...

(sorry for my english)

I am having the exact same problem on my 2 week old 2011 27 inch 3.4 i7 with 2GB Radeon 6970. Mostly artifacts on the dock and icons on the desktop.

Just today my new iMac i7 has started to get artifacts on icons and menu items while playing flash video and when doing some video rendering (so 100% CPU). It looked very similar to the problem I had with my old Macbook Pro when it got hot.

I installed the "desktop monitor" software and the GPU Diode is at 78'C, the GPU heatsink is at 72'C. They are the two hottest components in the machine. The top of the case is too hot to touch and the fans are no where near being at 100%, they are only running around 1400RPM.

I suspect this could be another issue where Apple have set the fan speeds too low to keep the system cooled sufficiently. I think I may take out AppleCare extended warranty as I lost out when my MacBook Pro finally failed because it was out of warranty.

Yes, I could install SMFanControl, but I'd prefer if my Mac did the job it was designed to do without having to mess around with third party apps.

My iMac has all the vents completely clear, and although it is a warm day it's not excessively so.

I'm experiencing similar problems, however it only happens in finder when I try to scroll, here is a screenshot:

iMac 27, 2011 with AMD Radeon HD 6970M 1024 MB

ps: it happens even when the mac is stone cold.

Right, an update. Ambient temperature is 21'C, GPU Diode was at 79'C and GPU heatsink 75'C.

Installed SMCFanControl as I wanted to test the idea that it was heat related artifacts from the GPU, once all fans at 100% and with all internal temperatures below 45'C - GUESS WHAT! No more artifacts.

I'm going to leave the fans at 100% as I don't want to damage my brand new iMac when I'm rendering video. I'll keep an eye out for recalls/fixes/exchanges though as you don't know what damage has already been done to the processors / PCB's.

Yeah, had the same thing in Console logs, and of course I meant i5 not i7 🙂

Model Identifier: iMac12,2

Processor Name: Intel Core i5

Processor Speed: 3.1 GHz

Number of Processors: 1

Total Number of Cores: 4

L2 Cache (per Core): 256 KB

L3 Cache: 6 MB

Memory: 4 GB

Boot ROM Version: IM121.0047.B0A

SMC Version (system): 1.72f1

Chipset Model: AMD Radeon HD 6970M

Type: GPU

Bus: PCIe

PCIe Lane Width: x16

VRAM (Total): 1024 MB

Vendor: ATI (0x1002)

Device ID: 0x6720

Revision ID: 0x0000

ROM Revision: 113-C2960H-188

EFI Driver Version: 01.00.544

I have a 2006 24" iMac. I've been getting artifacts, as well as occasional screen freezes (lasting about 20-30 seconds). Sometimes the screen freezes during video playback, other times when I'm just navigating around my system.

Interestingly, when the screen locks up I've had audio continue to play even though the video is stuck.

I've installed SMCFanControl and I'll tinker around with it to see if it helps.

Thanks for the idea.

I think this may very well be related to the other Lion (iMac 2011) freezing issue: https://discussions.apple.com/thread/3194165

I noticed artifacts in my menubar after watching a video on YouTube (which was flashing green intermittently). From what I've seen in the other thread, they get artifacts too as well as the freezes.

If they're related then it's likely a driver issue with Lion and these latest iMacs.

I'm seeing artifacting as well on my 2010 15" MBP with NV330M. I havent seen it in OSX yet, but in WoW if running in windowed mode and VMWare Fusion (3.1.3) running Win 7. Hopefully Apple gets this fixed pretty quick.