If everything was working fine before the new GPU it sounds like a bad card, and the best option will be to return it to the store and get a replacement.
Factory-overclocked GPUs often lack sufficient stability testing in my experience - it seems like they just pick a target that most GPUs should be able to hit, rather than testing every individual card.
Something like Furmark is not a good indicator of stability with a modern GPU that is constantly varying its clockspeeds dynamically - especially when it's crashing with older non-demanding games like DMC4.
If you want to confirm that it's the factory overclock, what I would suggest is to download the latest MSI Afterburner beta, set the core and memory clocks to something like -200 MHz and see if that stops the crashing. I would expect it to.
You could then adjust those values until you find something that remains stable. It shouldn't have to be anything like -200MHz.
The alternative is to keep the clocks at the default and increase the power limit (which I would do anyway). If that doesn't work, you could try increasing the core voltage.
I don't think I've actually received a factory-overclocked GPU which has been 100% stable out of the box.
I haven't run into problems like you where most games are crashing - which is why I would suggest replacing the GPU - but rather, one or two games would sometimes crash at random.
id Tech 5 games have a reputation for being crash-prone as a result of this. People insist their hardware is fine since other games don't crash, but after I dropped the clocks on my 900-series cards by 25-50MHz, the games never crashed again for me.
With my 1070 Strix OC, I have to set the power limit to 120% for it to be completely stable in games rather than bumping up the core voltage or dropping the clockspeeds.
Factory-overclocked GPUs often lack sufficient stability testing in my experience - it seems like they just pick a target that most GPUs should be able to hit, rather than testing every individual card.
Something like Furmark is not a good indicator of stability with a modern GPU that is constantly varying its clockspeeds dynamically - especially when it's crashing with older non-demanding games like DMC4.
If you want to confirm that it's the factory overclock, what I would suggest is to download the latest MSI Afterburner beta, set the core and memory clocks to something like -200 MHz and see if that stops the crashing. I would expect it to.
You could then adjust those values until you find something that remains stable. It shouldn't have to be anything like -200MHz.
The alternative is to keep the clocks at the default and increase the power limit (which I would do anyway). If that doesn't work, you could try increasing the core voltage.
I don't think I've actually received a factory-overclocked GPU which has been 100% stable out of the box.
I haven't run into problems like you where most games are crashing - which is why I would suggest replacing the GPU - but rather, one or two games would sometimes crash at random.
id Tech 5 games have a reputation for being crash-prone as a result of this. People insist their hardware is fine since other games don't crash, but after I dropped the clocks on my 900-series cards by 25-50MHz, the games never crashed again for me.
With my 1070 Strix OC, I have to set the power limit to 120% for it to be completely stable in games rather than bumping up the core voltage or dropping the clockspeeds.