If they lock it for Bios editing they will lose a lot of customers, the miners. And since the miners are the majority of customers of AMD, they were never good enough to fight Nvidia in gaming , it can be a suicide move for them so I don't think they will lock the Bios editing feature found in the Polaris 20 cards.
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It is tempting to go over to the green-green side
There will be ways to go around a BIOS lock. People will consider hacking through locks if the risk of voiding your warranty/RMA (some have already enforced it) is nothing compared to the benefits you will reap. But like hell that’s gonna happen. If it’s locked, it stays locked, for majority at least.
I agree. It may be some time until a tool's developed to easily mod the cards to make them bios moddable, but it'll likely happen eventually even if the BIOs is locked. It'll be interesting to see the methods employed to lock the BIOS if AMD chooses to go through with locking the cards.
It'll also be interesting to see what the pricing for last-generation 500- and 400- series cards goes down to after the launch of the 600 cards. The last gen cards are already extremely cheap, with prices falling below $90 in some places, which aren't too bad of a choice if you have cheap enough electrical rates.