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.
Once I got the new Win10 update, I could no longer change the timings on the fly with Claymore running. Even with the 19.4.3 driver. I tried all of the recent drivers I could find.
Going back to the 18.9.2 driver allows me to dynamically update using AMDmemTweak again while Claymore 11.9 is running under the newest Win10. 19.6.3 still didn't work. It took quite a while to crawl back to 18.9.2 to find one that worked.
EDIT:
Well, I spoke too soon. I was able to do it briefly but then it locked me out again. I don't know what the solution is other than making sure to modify before running Claymore. But it sure was nice for a while to be able to bring up the GUI version and modify timings on the fly while Claymore was running to see the effect.
I use 19.4.3 drivers with GUI version of tool. Latest Windows 10. All changes via GUI tool affects on the fly on 14.x Claymore miner. But Claymore must be launched without strap and rxboot options.
Well... I'm not sure its still relevant (apparently it was for me), as I've missed good few months since this wonderful tool has been released.
Anyway it seems there is some confusion with applying settings to the GPUs so let me state my findings:
I use it under win10 (1607 Anniversary edition) with 18.6.1 driver for both Vegas(with PPTs) and Polarises(modded bioses).
For both I also use ODT for clocks and voltages, also I don't like disabling any stages.
Basically by switching default REF=5 for Polarises to 10 and reducing RFC a bit I can get over 3% increase in ethash output.
What I noticed however is that while REF is applied more uniformly (I can 'probably' do it before running the miner - before GPUs are in their target frequencies range)
The RFC is not applied. So in order to get it properly working I have it(CLI version) scheduled to run after some delay, when the miner is already running.