Important: The setting MUST be applied before mining starts or the value won't change. Even if I closed the miner and tried to apply the setting, it would not take. However, applying via .bat after reboot before the miner started worked great.
This is not true. AMD driver 19.4.3. I change REF on my RX 580 cards during mining and it applyies and changing the mining speed.
I used to be able to do this but can no longer change on the fly after the Win10 update and a driver update. I may try to go back to older drivers and see if that changes. To me, that was the best part about the tool ... changes on the fly to see the effects.
In fact, once I run Claymore, I can't change any values even after I stop Claymore. I have to reboot to make the values modifiable again.
This is Claymore 11.9, not the newer 14.x stuff that uses this same mechanism to adjust the card timings. I can see where that might conflict. But 11.9 was allowing mods during mining previously.