What are your Memory Clock settings?
I have mine at 2150 and the Core clock at 1244 and it just crashes the machine after mod.
I have set -h at 1024 and 960, both crash the machine.
Mem 1960-2000MHz depending on rig. The strap is a lot more optimized, giving huge boost, especially to cryptonight for some reason. I don't set h, but default for newer miner is 1024 , with dmem 1.