I tried to reproduce the issue with clocks and low speed until miner restart.
Windows 10, latest blockchain drivers, stock RX580 Nitro+.
1. No overclock: If I start miner in ETH-only mode, it shows about 16MH/s only (and low memory controller load in GPU-Z) and I see this speed for about 20 seconds, then it shows 24.6MH and works fine. For dual mode it shows full speed immediately. Unfortunately, I have no idea why GPU works slowly within first 20 seconds, it is something related to drivers.
2. I close the miner and apply some changes in clocks: memory 2000 -> 2100, core 1300 -> 1100. When I start miner, I see that it applies new clocks in about 10 seconds, but still shows 18MH/s only for first 20 seconds. Then it shows about 25.5MH.
Note that I use default ROM so these speeds are not high.
3. I close miner and apply new clocks again: -cclock 1000, -mclock 2050. Same behavior: it shows low speed at start, then normal speed for these clocks. GPU-Z shows changes in clocks in about 10 seconds after start.

So right now I cannot reproduce the issue with new clocks: in my tests new clocks are applied immediately, I don't need to restart the miner or reboot the system.

disabled secondary monitor and rebooted and I can control memory clock in wattman, but it's still bouncing to 1000 mhz and getting messed up hash

Claymore 9.8
AMD Driver [Suspicious link removed]p*ute
Gigabyte RX 580 Gaming 8 GB

Voltage doesn't work with Wattman and AB beta 16 or Trixx.

yes you can. my powercolor 470/4 samsung gets 29.3. just strapped 1750 upward. 1040/2100 clocks. my msi 470/4 with samsung gets 27 with same settings. not sure why the msi is lower. kvm is plugged into the powercolor

also this is dual mining sia -dcri 15 setting. each is doing ~400 mhs sia.

so all i did is the memory straps, nothing else in the bios was touched except i raised the power limit from 5 to 25 on the powercolor.

it is possible the 29.3 mhs rate is an error possibly? however rig is stable for weeks at a time, and that card shows no artifacts when displaying the desktop.

Increase RAM clock to 2200 (or close to that, what is stable for you)
Decrease GPU: 1200 MHz
Decrease TDP: -10%

With bios mod, it should give you 28-29-30 depending on the driver/miner version. (I suggest latest available from both + Creative Update for Windows)

Does anyone know what the most common/probable causes are for a gpu hanging?  One of my RX580s hangs after about 15 or 20 minutes every time.  Very frustrating.