Could be a reason if you run any other software. Not sure that hwinfo shows the right information about, use any Watt meter device at your power cord is better. One important hint - use the OverdriveNTool version 0.2.1 beta - it has direct access(press right mouse button at the tool) to the powerplay area in the registry, so you can adjust some values directly(after that reboot the settings are active) - you must start this tool with admin rights to get access to the registry. Have fun.  

With Claymore 10 and asm I get 43.8 - quite close to 44.2 - good job so far, thanks.

Short correction to the hashrate - I have 43,5 Mh/s ! with these settings ..... not 42,5 Mh/s , sorry for the typing error....but even better :-)

thanks - good hint - will try it !

Got it now for Vega 56 - W10 installed, just use the Monero hints posted on reddit (Monero and Vega - the definitive guide), use Bios from Vega 64, AMD blockchain driver, use DDU before, if any driver was installed, after blockchain driver installation set in Wattman all voltages to manual, import the Vega_64_Reg_GPU_0000-1050HBM.reg (powerplay pre-settings), with OverdriveNT - adjust P7 1060 /865mV and mem P3 1090 / 875mV.
Got a stable hashrate of about 42,5 Mh/s on ETH with Claymore 9.8 with 230 Watt at the wall. Think that is the maximum actually....sadly not the 80...90 Mh/s as posted in any fake posts

Read in some other postings, that 43Mh/s possible, but Vega models seems to be sensible using the correct driver. I tested last days the Vegs 56 and found, that the AMD mining optimzed driver pushes the hashrate up to 42Mh/s, but with a high power consumption of about 250 Watt at the wall. Using the standard driver 17.9.xx I got up to 38Mh/s with 140Watt only (optimized voltage 875mV, CPU 1000Mhz, Mem 1050mhz), what is not so bad in terms of efficiency - but we all expected much more in the past from these new models.

I get from my Nitro+ 4GB RX570 /Hynix) max 30,5Mh/s out at 120W at the wall. Used the Ubermix 3.1 strap copied from 1650 up. Undervoltage at 860mV both. Clock at 2070mem/1160GPU. That's it.

I checked today a Vega 56 and Ethos 1.2.4. - Ethos has no driver for Vega. Windows 10 works and delivers about 40Mh/s on ETH.

Im using 2xRX580 and 1xRX570 in one RIG with the new driver. Get from RX580 about 30,7Mh/s constantly, the RX570 Nitro+ delivers 29,6Mh/s - with a patched BIOS.
The undervolt process is done by the OverDriveNTool-which works good - so the whole RIG with these 3 RX and a constant rate of 90,8 Mh/s pulls 400 watts at the wall.
Below 850mV the RX5xx will get unstable at MEM 2100 and GPU 1150 Mhz. I think more optimization is not possible with this technology. Let me know if I'm wrong.

Try the new AMD beta driver and Clymore 9.8, then you can get some more out
Link: http://support.amd.com/en-us/kb-articles/Pages/Radeon-Software-Crimson-ReLive-Edition-Beta-for-[Suspicious link removed]pute-Release-Notes.aspx

Have the Nitro+ RX570 too, but with 4GB - with Hynix RAM.
Used the stripe from bughatti or Ubermix 3.1 (the same) from 1625 up and reduced voltage to 900mV. Depending on your miner used you get different hashrates. The best rate I got actually with the newest Claymore 9.8 version is 29,8Mh/s - by using the new AMD beta driver(called Radeon Crimson relive Edition Beta for [Suspicious link removed]pute) on Windows 10. With Ethos(Linux based miner) I got only 26,6Mh/s. Another parameter impacting the hashrate is the RAM-type - Elpida slower, Hynix fast, Samsung fastest.
Optimize GPU and Mem-Clock - I got the best results with: GPU - 1170 Mhz / MEM - 2080 Mhz. Check the best values for you with MSI-Afterburner. Keep in mind that you need the atik-mdagpatcher, if your BIOS is changed or the new AMD-Beta-Driver is used.
Hope that helps to get better rates out.

I got from a RX570 nitro 4GB with Hynix and a strap from bughatti(was the best in test of 6 different) in max 28,5 Mh/s out (tuned with 875mV), with a 580 I got 29,5 Mh/s - all stable. The clock max. 2070MHz.
Just to give you a feeling for realistic values.

Update aug 20th: with the new claymore 9.8 and new AMD beta driver blockchain optimized, I get now 29,7Mh/s with the RX 570 and 30,8Mh/s with the 580
https://postimg.org/image/kou9fjcjd/

Dear all, would like to post my findings about power consumptions - I use RX580 with 4GB - the normal polaris and one 570 nitro. I'm measuring the whole power consumption of a rig. The board with cpu is consuming about 60W. A whole rig with 2 RX580 and the 570 consumes about 500W - this means a power consumtion of 150W per RX. With the tuned RX580 I get 28Mh/s and with the tunded RX570 nitro+ about 27Mh/s. I expected more from the nitro+ (has Hynix), but I checked several stripes - no way to get more out. Think experts like matttev can get the last percents out, but I don't think it's possible with only 80W per RX580. It all depends on how to measure the power consumption - it's easy to get wrong on that.  

welcome

I optimized my RX570 nitro+ with 4GB Hynix, got about 138W power consumption. My parameters: BIOS parameters: 1150GPU/2060Mem/0.9V Mem/0.86VGPU. Got the best results with a custom strap, not by copying the existing 1500 strap above. These data are generated with EthOs not Claymore. During tests with claymore I got hashrates of about 29,6Mh/s by using the same parameters.With EthOs max. 27Mh/s only.

got the last one, sorry. It seems that we all have to buy expensive cards either in the 2nd market like ebay or wait til AMD can produce more. Nobody knows actually when the availability will be better as long as a lot of new guys or companies join into the mining area. 

@Mattthev - sure that your ETH-Wallet-ID is correct, seems 3 digits are missing

Optimized today a RX570 Nitro+ 4GB - got 29,5 MH/s with the Glaymore miner under W10 and BIOS parameters: 1150GPU/2060Mem/0.9V Mem/0.86GPU with Power consumption @90-100W.
I agree on Mattthev notice getting more out, but with good knowledge of certain VRAM behaviour and long test scenarios - but possible.

Got a RX570 nitro+ 4GB some days ago. Strange - has the same VRAM-Types - one Elpidas and one Hynix like RX580.But Hynix, instead of the RX580 Pulse 4GB, has the Hynix as the main VRAM relevant for tuning. I optimized successfully the BIOS by trying several straps - found the right one at the end. Got 29.8 MH/s - quite good, but only with the Glaymore miner under W10 and BIOS parameters: 1150GPU/2060Mem/0.9V Mem/0.86GPU. Power consumption @90-100W. With Ethos-OS I got only 26.5MH/s - anybody an idea why? If any questions - just ask for.