Dont know if this BOINC snapshot.png will work but here goes anyway.
[img]/Users/michaelgrissom/Desktop/BOINC Manager001.png[/img]

Hello everyone!

Long time GPU problem since a previous BOINC update - not intermittent.

Running BOINC 7.6.22, ATI Radeon HD 4850 512MB R700GPU, iMac 2.8 GHz Core i7 (late 2009) OS X 10.11.6 16GB 1067 MHz DDR3.

I'm guessing that somewhere during previous BOINC updates, my GPU became incompatible with BOINC and I haven't found any GPU patches to make it compatible.

Any suggestions would be greatly appreciated.

You will have to upload your snapshot to Photobucket or similar image server and link to it there for us to be able to see it.

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I`m not sure there is an appropriate app for HD4 but it would be better to move this thread to NC so Urs and TBar can have a look at it.

WARNING: This application needs newer GPU, at least ATI Radeon HD 5000 needed, exiting !

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With each crime and every kindness we birth our future.

Experimenting with how to post my image using Flickr...

BOINC Manager001 by Michael Grissom, on Flickr

Got it! BBCode works.

Thanks Mike. I previously searched and found an upgrade to a ATI Radeon HD 5000 (https://www.ifixit.com/Guide/iMac+Intel+27-Inch+EMC+2309+or+2374+Graphics+Card+Replacement/9553) but the reviews said the increase in speed would be "barely noticeable" and expensive. So, the upgrade to a 5000 series would only be needed to run BOINC and I can't justify the cost just to add the GPU to my 88% CPU crunching speed. Oh well.. :(

There are still a couple of those iMacs with the 4000 series cards on Beta. Just so you can see how they run with the Apps at Beta, https://setiweb.ssl.berkeley.edu/beta/results.php?hostid=77906
The bottom line is the CPU runs the BLC tasks just as fast as the GPU, when the GPU works.
If you look at the App list for Main there isn't an SETI@home v8 App there that will run the HD4000 series GPUs, scroll all the way to the bottom, http://setiathome.berkeley.edu/apps.php

If you aren't planning to try using the GPU at another Project the best thing to do is uncheck the ATI box in the Preferences http://setiathome.berkeley.edu/prefs.php?subset=project You could tell BOINC to Ignore the GPU also, <ignore_ati_dev>0</ignore_ati_dev>