Edit:
I moved the intensity to 19 and it gives a stable hash of 423. At 20, it still works but pc starts to lag and I can't do anything else
Updated:
With Sapphire R9 290x BF ed, I'm using the below to get stable 436 KH with zero hardware error. Any other setting and tons of HW errors start coming in. I think the thread concurrency did it for me. Has to be 2816*8 for this card. Don't ask me why (though I'm a computer engineer; just not very upto speed with AMD chipset). Also I run the fan at fixed speed of 75% from Trixx to keep temperature below 75C.
setx GPU_MAX_ALLOC_PERCENT=100
setx GPU_USE_SYNC_OBJECTS=1
COLOR 0A
vertminer.exe --scrypt-vert -o -u -p -I 20 --lookup-gap 2 -w 256 --gpu-engine 1000 --gpu-memclock 1500 --thread-concurrency 22528
