AMD RX Vega 64 Mining Benchmarks with various OC/Underclock and Energy Consumption Information

Hello everyone I recently got the new AMD RX Vega 64 GPU. It's pretty decent, but at first glance I noticed it uses two 8-pin PCI-E power wires, which just screams power-hungry. None-theless I looked into what it could do using NiceHash'es mining benchmark software.

For reference, I monitored my PC in Idle mode to differentiate the GPU's power draw. Looks like with a ThreadRipper CPU idle with 128GB RAM runs about 150W avg.

So, next I started and measured stock settings with NiceHash. All benchmarks were done using the most profitably found mining algo at the time, Hashimoto+Pascal mining.
Results: 445W - 31.985MH/s - stock settings.

The options I tweaked were: Power Limit, Voltage to Memory & Core, MHz to Memory and Core, and Fan Speeds. For reference, I use PL as an abbreviated form of Power Limit.

The worst performance for energy cost I found was with only the modification of +100MHz to the Memory speed:
450W - 2.916MH/s - +100MHzMemClock

I found the largest affector of power usage was setting the Power Limit %. With the recommended limit of -20% Power Limit, I found I could reach as low as 385W, with a pretty decent hit to hash rate:
384W - 29.139MH/s -200mv mem +155mhz mem PL-20%

I found the tempurature was maxing out over 80 degrees celcius at this point, and raised the fans speed by 800RPM, to allow for it to continue stable operations for long periods. This increases the wattage use by around 15W.

Finally, I found the greatest Hashrate gain with the least power limit reduction in this setup:
415W (400W with old, default fan speed) - 32.936MH/s -200mv/+155mhz mem PL-8% -50mv-5%Mhz core +800RPMFan

As you can see I can reduce the W draw by 30W while gaining 1MH/s using these settings, which can be large considering how many GPU's can be used mining. Either way, this power draw is still quite large, but should return some decent profit.

If anyone has questions or comments to add please do, I'd love to see what you all are doing to get the most out of your hardware. Have a good day.