The TLDR on this is that it's assumed to be FUD by NiceHash to try and get people to move to their new platform, or that they were honestly just trying to 'protect' their client base...+1 on nicehash.
Use Nice Hash OS: https://www.nicehash.com/nhos-mining
Set TDP to 'Low' which would probably yield best ratio to power consumed vs rewards and lowest tear on the GPU.
Also do note:
STOP using Phoenix miner immediately!
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It has come to our attention that Phoenix miner is no longer available for download from its original download location. Control shasum from new download locations does not match the value published by the developer on his channel! This brings the possibility that the Phoenix miner's author wants to cover its tracks and disappear or even do something malicious.
We have immediately disabled Phoenix miner from NiceHash Miner, and we advise everyone to stop using Phoenix miner immediately!
Phoenix miner is a mining software from an anonymous author. It is not digitally signed, and no one knows who the creator is. This brings serious risk to anyone who will continue to use this software! Do not try to download Phoenix miner from any 3rd party source since it could be fake and malicious!
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Source:
NiceHash - Leading Cryptocurrency Platform for Mining and Trading
www.nicehash.com
Cheers.
Anyways, the dev from Phoenix has been publically out and about refuting this.