Rx 480 4 GB OC on Linux

I'm mining ZCash, currently around 280 H/s on one amd rx 480 4GB on Linux ( kali linux 2016.2 bc it's a debian distro with default kernel version compatible with amdgpu-pro drivers ).
I want to squeeze a lilttle bit more out of my brave card, but have failed to do so :(. I don't know how to install adl SDK, seems like it's not compatible with linux so my gpu miner can't OC my GPU ( claymore GPU driver ).
I have tried to OC my GPU before launching miner with:
echo 5 > /sys/class/drm/card0/device/pp_mclk_od
command. But it only made GPU to mine at idle 300MHz memory frequency ( not only on claymore but also on silentarmy).
I don't want to flash my GPU and loose my warranty. Any help pls?

I'm also mining the same 280 H/s on one AMD RX 4 GB but in Windows 10... so any pointers on increasing the rate would be highly appreciated!

Have you tried OC your GPU? Post the results pls. You use Claymore's miner too right?