It is quite finicky since everytime it starts, it drops my clocks to 100/150 and voltage to 0.95v(I hate it). Yet, it doesn't come with a voltage monitor to find out whether you set it right. Conversely, MSI Afterburner can correctly check whether its own input voltage modifications passed through.
So, you will need not 1, not 2, but 3 software tools in my method: Asus Gpu Monitor to verify ATT's modifications & MSI Afterburner. MSI Afterburner is sometimes unable to intercept parameters in presence of ATT, therefore if you notice MSI Afterburner not working, you go to the other tool and try and adjust from ATT all the while checking whether things are working through Asus Gpu Monitor.
Just pick your reference clock and reduce voltages & clocks preferrably via MSI AFTERBURNER, not ATT since its voltage steps are more coarse(0.05v steps rather than 0.005v) and fire up "3D renderer > find max gpu". It will start finding single errors and backing off momentarily followed by rechecking that next integer frequency. Note both voltage & frequency (decline 2 mhz for safety) and keep filling the frequency plot along your target voltage range. Once done, you will have your own performance profile.
You add extra voltage settings by clicking the ellipsis next to the voltage level.
Warning: Spoiler! (Click to show)
Also, in exceptions Asus Gpu Monitor doesn't notice when ATT's voltage modifications wouldn't apply. At those moments, checking the MSI Afterburner monitor will reveal an absence of voltage change from the point in time chart it should be graphed.