I know tomshardware did some tests to show that the Fury could undervolt pretty well while maintaining it performance and I was curious to try this myself. I used a P3 International Kill a Watt to measure power consumption at the wall. I did this using 3DMark Firestrike and Furmark GPU stress (1080, no MSAA).
i7-6700k @ 4.6
16GB DDR4 3000
MSI Z170A SLI
250 GB Intel SSD
250 GB Crucual SSD
1TB WD Blue
DVD Drive
4 Case Fans
EVGA 550 GS
Sapphire Fury Nitro (Custom fancurve, 30% at 60C)
Firestrike / Furmark GPU Stress
1050/500 No Undervolt
Temp ~ 78C
Total Score: 13629
Graphics Score: 15793
Firestrike Wattage: 370W
Furmark Wattage: 440W
(Core could only maintain around 1000mhz)
1050/500 -72mV
Temp ~ 76C
Total Score: 13611
Graphics Score: 15876
Firestrike Wattage: 330W
Furmark Wattage: 390W
(full 1050 mhz acheived)
900/500 No Undervolt
Temp ~ 68C
Total Score: 11952
Graphics: 13773
Firestrike Wattage: 240W
Furmark Wattage: 330W
900/500 -72mV
Temp ~ 65C
Total score: 11958
Graphics score: 13782
Firestrike Wattage:200W
Furmark Wattage: 290W
750/500 No Undervolt
Temp ~ 63C
Total Score: 10226
Graphics Score: 11532
Firestrike Wattage: 210W
Furmark Wattage: 260W
750/500 -72 mV
Temp ~ 62C
Total Score:10251
Graphics Score: 11571
Firestrike Wattage: 190W
Furmark Wattage:230W
Looking at firestrike scores online the 900/500 gets roughly 390X performance and the 750/500 gets around non overclocked 970 performance. While this isn't apples to apples with games it was interesting to see how well the performance scaled with power usage.
i7-6700k @ 4.6
16GB DDR4 3000
MSI Z170A SLI
250 GB Intel SSD
250 GB Crucual SSD
1TB WD Blue
DVD Drive
4 Case Fans
EVGA 550 GS
Sapphire Fury Nitro (Custom fancurve, 30% at 60C)
Firestrike / Furmark GPU Stress
1050/500 No Undervolt
Temp ~ 78C
Total Score: 13629
Graphics Score: 15793
Firestrike Wattage: 370W
Furmark Wattage: 440W
(Core could only maintain around 1000mhz)
1050/500 -72mV
Temp ~ 76C
Total Score: 13611
Graphics Score: 15876
Firestrike Wattage: 330W
Furmark Wattage: 390W
(full 1050 mhz acheived)
900/500 No Undervolt
Temp ~ 68C
Total Score: 11952
Graphics: 13773
Firestrike Wattage: 240W
Furmark Wattage: 330W
900/500 -72mV
Temp ~ 65C
Total score: 11958
Graphics score: 13782
Firestrike Wattage:200W
Furmark Wattage: 290W
750/500 No Undervolt
Temp ~ 63C
Total Score: 10226
Graphics Score: 11532
Firestrike Wattage: 210W
Furmark Wattage: 260W
750/500 -72 mV
Temp ~ 62C
Total Score:10251
Graphics Score: 11571
Firestrike Wattage: 190W
Furmark Wattage:230W
Looking at firestrike scores online the 900/500 gets roughly 390X performance and the 750/500 gets around non overclocked 970 performance. While this isn't apples to apples with games it was interesting to see how well the performance scaled with power usage.