for the HD 6990 and SDK 2.5, is it still true that I have to connect a monitor (or fake a monitor by using a special connector) in order to have the GPU recognized?
no it should be possible use GPU in headless enviroment.
I don't recall the 6990 being a supported GPU. Have you gotten it to work with both devices showing up?
No, unfortunately, I don't have a 6990 yet. Currently they seem to be unavailable, at least here in Germany.
What I have is a 5970, which also was unsupported for some time if I remember correctly. However, I'm using CAL and IL, and those always found 2 GPUs. So I'm hopeful... I don't have any experience with OpenCL, though.
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