A few questions about the R9 290x

This is my first post, I have just built my first system and I need some help getting the most out of it.

I am getting 190 kh/s per 290x when brute forcing against a wpa2 hash, but I have heard people say they get over 200 kh/s per card.

Is there something I should do to optimize my system?

Also I read an article titled AMD R9 290X As Fast As Titan X in DX12 Enabled 3DMark – 33% Faster Than GTX 980.

This made me wonder if dx12 will make r9 290x faster for password cracking.

thanks