Is the overclock function actually work on Simplemining?

I'm using the RX OS dagfix and tried changing the settings to something like core 1150, mem 2200, undervolt 900, my hashrate is lower than normal. I replicate this with afterburner, the results are the opposite. I tried bring the value close to stock, my hashrate got messed up, it's like I'm better off not doing anything.

I even tried with just undervolt 975 --> 950 --> 925 --> 900 just to see if it is working. My cards are drawing the same power of the wall as stock. I tried by bringing down the powerstage to 6 --> 5 --> 4, it's still drawing the same power. It's like nothing has changed.

Each time I change the overclock settings, I hard reboot (power off and on) the rig just to see if that works. Apparently it did not.

I have a 8 GPU RX 580 rig and a 12 GPU RX 580 rig which is currently trying out using simplemining. I can't seem to get overclock to work, either drop of hashrate or power stays the same.

Can anyone advise what I did wrong?