No probs.
I use the manual option for overclocking/undervolting, it has it's own section where you can specifically target a certain voltage limit/requirement.
Think of a GPU like a CPU, where it has different 'STATES' / 'C-STATES' / 'POWER STATES', like these:
Idle frequency: (300/333mhz) = GPU in this state when you're using your PC for non-graphically intesive workloads like web/folder browsing/using basic apps.
Frequencies under load: (several power states/options) (mine is 1411Mhz or 1430Mhz or 1450Mhz or my overclocked one).
You want to select Manual Voltage limits and you should see a bar similarly to your Fanspeed curve, but for voltage (you may need to update your Drivers to a later version to see this..and I highly recommend Adrenalin 2019 version, as long as you don't see any issues with the app, cuz they added a lot of really cool features).
Something like: for Idle frequencies level you'll get 800-900mz // for 'under load' frequency, you'll get 1120mv or higher.
This is what you want to reduce, the one under load (you could always get MSI Afterburner as it has a slider for the voltage, which is easier to use than Wattman, but it may mess with your fanspeed curves that you created.
What you do is reduce the mv by tiny increments (move it 1 step lower, so if you have 1120mz, it becomes 1100mv, or whatever.
You could also, alternatively just reduce the Power Limit slider bar (works in Percentages %), this basically reduces the amount of "total gpu power draw, in watts" I believe (someone correct me on this if I'm wrong please, thanks!), reducing it also by only 1 step (-5% or -10%) will help your total GPU Power Consumption not get as high, but you might see a slight drop in frequencies for your GPU (meaning a little less performance).
This is why I usually recommend the 'undervolting' technique..as you can keep the frequencies and performance you are currently have, yet consumer less power, and as a result produce less heat, so you can lower your fanspeed even lower.
Some instability is expected, so stress-testing your GPU is recommended, if undervolting, but all it will do is crash/freeze the GPU, and upon reset, your undervolting settings will revert back to stock settings (that reminds me..save a profile of your custom Fanspeed Curve before undrevolting, or else you'll have to set it up all over again, if you lose the settings from a GPU system freeze from undervolting too far
If all this isn't clear, I would need a couple of images of the
complete Wattman Control Panel (all options visible, when scrolling up/down), to see exactly what options are available to you.
Good luck!
