Most of my machines run Linux and none of those have anything but an el cheapo mobo with integrated graphics. I have some windows machines with ATI HD 4850 (512MB) cards but they are 'in production' at Milkyway and my suspicion is that the app here wont run on them anyway (insufficient memory and OpenCL 1.0).

However, courtesy of my daughter's business, I do have access to a nice group of iMacs of the late 2009 to mid 2011 variety, with a variety of different GPUs and all running Lion 10.7.2.

I tried a 27" iMac, late 2009, core 2 duo, HD 4670 GPU. OS X reports the GPU as having 256MB RAM and BOINC 7.0.11 says it is OpenCL 1.0 and 512MB RAM. Because of the memory discrepancy I gave Collatz a spin first (lower memory requirements) but that immediately locks up the entire machine and a power cycle is needed to restart.

I then moved on to a 21", early 2011 i5-2400S with a HD 6750M 512MB GPU. BOINC 7.0.11 sees this as OpenCL 1.1 and 512MB so at least it looks hopeful. Once again I attached to Collatz and this time was immediately rewarded with tasks that run and validate. So, time to try Albert. A task runs for a few seconds but then errors out. The stderr output says

<message>
process exited with code 229 (0xe5, -27)
</message>

and

[18:40:16][1258][ERROR] Error in OpenCL context: [CL_MEM_OBJECT_ALLOCATION_FAILURE] : OpenCL Error : clEnqueueNDRangeKernel failed: memory usage (268435456 bytes) is more than the device can support (201326592 bytes)
[18:40:16][1258][ERROR] Error during OpenCL FFT setup (error: -4)
[18:40:16][1258][ERROR] Demodulation failed (error: 2021)!

along with a raft of warnings about unused variables.

OK so not enough free memory to run the app, it would appear. As I said, the machine is in a work environment so not really suited to running these tests. However I was running it on a public holiday and there was nothing else running on that machine and it had just been rebooted after the install of 7.0.11. Does anyone know how to free up extra memory on an OS X machine without making it difficult for the real user to do what they need to do when it isn't a public holiday? :-).

So, onto a third possible candidate. This machine is late 2010, an i5-760 with a HD 5750 1024MB GPU. BOINC 7.0.11 agrees and also says OpenCL 1.1. Collatz runs fine as expected and this time so does the Albert app. The first task done has even validated against one done by the CUDA app, so I'm quite happy about that. It's now not a public holiday any more and the machine is in use and I haven't had any complaints so far (there are 4 FGRP CPU tasks and an atiOpenCLLion task running). All the iMacs in this office are running the standard project anyway so the users are accustomed to seeing the BOINC icon in the dock. They seem to be able to do their work just fine.

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Cheers,
Gary.

BOINC 7.0.12 is out, with lots of OpenCL bug-fixes. Links available in the change log thread.

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Jord.

BOINC FAQ Service

They say most of your brain shuts down in cryo-sleep. All but the primitive side, the animal side. No wonder I'm still awake.

Thanks. I found another suitable iMac, late 2010, an i5-760 with a HD 5750 1024MB GPU, just like the previous one. BOINC 7.0.12 is now installed and the first atiOpenCLLion task is underway. If this one makes it through the night I'll put 7.0.12 on the very first iMac I tried and see if that makes any difference to the reported GPU RAM. Maybe I can get that Collatz task underway after all. It's still sitting there suspended.

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Cheers,
Gary.