I set intensity to 13 on my 290x, it stays at 0. If I go up to 14 or 15 HW starts creeping up. Not sure what it is, I optimized the hell out of my settings.
Anyway, I managed to reduce my HW by setting thread-concurrency to 8192 but that is hardware specific. you should google what the best setting is for your rig.
What does Hardware error actually mean and how can i reduce it?? in the last 4 hours cgminer says HW is 157.