OK - went and checked. I have no idea what this means:
Max combined load on +12V is 50A, 3V and 5V Not exceed 140W, Max Continuous Output 700W
+12V1/16A, +12V2/16A
+12V3/18A, +12V4/18A
+3.3V/24A, +5V/24A
Your PSU manufacturer is claiming a total of 68 amps on 700 watts; an impossibility. The most you could get is 58 amps but again only at 100% efficiency, another impossibility. They likely rated the amp load under peak power output which may last for only a few seconds but it looks good if your trying to get a "high power" supply cheap. In reality you're usually just getting a "cheap" PSU.
This leads me to believe you have a less than reputable PSU in your system and at that point there's no telling what kind of power your actually getting to your video card or how clean or stable that power might be.
I'm guessing your old video card needed less power than the new one. Since that's the only thing that's changed in your system it's highly likely the flaws in your PSU are now showing themselves. Continued underpowering of your video card will eventually burn out the PSU, the card or even the motherboard.
I'd highly recommend sticking with reputable PSU manufacturer's like Corsair or Seasonic who don't over rate their PSU's and are known for producing clean, stable power. Yes, they cost more but you get what you pay for and your power supply is probably the single most important component in your computer.
BTW, you have 4 +12V rails. There's been a lot of debate over what's better; single or multiple rails but I prefer a single rail PSU. At least you know how it's wired and that the power you need will be there when you need it. I use a 80+ certified (rated 83%) single rail PC Power and Cooling 750W (825W peak output) Silencer providing up to 60 amps (87% efficiency @ peak output).