I recently bought a Sapphire Pulse 6700xt and I'm experiencing this odd situation when undervolting.
Normally when tuning a card like the Powercolor 6700xt in my other rig and applying the undervolt when the card become unstable the drivers will crash and heaven benchmark freezes briefly and I get the message from adrenalin saying everythings been reset to default etc and all's good I can go back into adrenalin and start over. Mt friends Asrock 6700xt is the same.
However on the Sapphire Pulse card after a driver crash the screen will just go blank and lose all signal, after rebooting the PC I cannot relaunch adrenalin and I get a message which tells me the version of AMD software I have is not compatible with my AMD graphics driver and I have to remove and re download adrenalin all over again which is a pain if I have to do that each time I want to find the optimum undervolt settings.
I thought perhaps this was just a bad card (to be fair it probably was as it ran a little hot and didnt undervolt very well and didnt handle ram overclocking well either and I expected a little more from a sapphire after hearing good things about the brand) so I RMA'd the card and bought another one, but from a different retailer. Same issue (only this card is a nice one, undervolts really well and handles ram overclocking way better, about 7 degrees cooler and quieter under load than the other sapphire) so I dont want to get rid of this one. It's not too much of an issue as once I find the settings I'm happy with it is a case of set it and forget it but just wondered if anyone else has experienced this with a sapphire card or what could be the cause of it? As I say my powercolor 6700xt does not do this in either system and this appears to be a characteristic of the Sapphire Pulse card.
Also the driver is not compatible message I think it's related to the windows update replacing your current drivers. Try to use DDU and there should an option in there to stop windows from updating the drivers. Select that when you delete the drivers with DDU.