Not exactly uncommon - you could RMA it, but is it worth a 10% hashrate boost to lose time waiting for a replacement? Have you tried 947 engine?
I found these card are undervolted - when high stressed it just cant make it - but in games - ok , yet...
orginal vddc - 1.020 (stress) at 1.070 (stress) should be fine still testing
I have to check every single one