That GPU-Z shot doesn't include any load values, only idle values, so it's not useful. But when you do actually run a test like looping Heaven bench for a few minutes, you should pay attention to:
- When overclocking: GPU Core Clock - confirm the clock frequency is indeed what you set it to in Afterburner
- GPU temperature - make sure it stays below 80C or so
- GPU load - confirm it's mostly 100%
- VDDC - this should change whenever you adjust voltage in Afterburner, but it won't show the exact same reading. What you set in Afterburner is a nominal value, while VDDC is the actual voltage supplied (though I'm not 100% sure if GPU-Z is accurate in this respect, but it should still display changes to voltage)
And if you use HWinfo64 you should also see VRM temperatures, depending on whether your graphics card supports it.
Update your drivers for Intel Rapid Storage Technology and ASMedia SATA3: http://www.asrock.com/mb/Intel/Z87 Extreme4/?cat=Download&os=All
What voltage were you at (in Afterburner)? I needed to increase my card's voltage to get 1100 stable.
70C is low enough that you have room to increase voltage.
Yes, if it's driving two displays it won't downclock and downvolt properly. To avoid that, you can connect the secondary screen to the integrated GPU.
A benchmark freeze is a very expected symptom of the overclocking process. All you have to do is add more voltage and/or back down on the clock speed to get it stable. It's a trial and error thing
What type of cable are you using to connect your monitor?
If you're seeing artifacts, that means the clock is too high. Every GPU has its limits at a given voltage. You could try putting the old BIOS back so that you can tweak the voltage again.