I had the same problem.

Assuming you are using Windows, press and hold the Windows Key, then press R. to get the Run dialog to show.
In the run dialog, enter this and press OK:

setx GPU_MAX_ALLOC_PERCENT 100

Note that it must be entered exactly as shown. IT IS CASE SENSITIVE.

You should then be able to increase thread-concurrency, and also your intensity, without getting HW errors.