Help overclockin my Sager 8651 (Clevo P650SE)

[Corpius]

Sager 8651 specs:

Intel i7-4720HQ

GTX 970M 3GB

8GB RAM

Samsung EVO 850 (250gb)

1 TB 7200RPM HDD

I'm new to the whole overclocking thing. I just flashed my vBios with Premamod. The flash was a success. I've been using Nvidia Inspector and EVGA Precision (I have MSI Afterburner as well). If anyone has the same laptop or GPU, what was the most stable OC you got? Is the highest overvoltage you are able to take the card +212.5 mV (max 1.200 V)? Also, why is my power target locked on every overclocking software I've used? I've seen people having the ability to change it freely, but mine seems locked even after the vBios flash. I think my main issue is how to raise the power target.

UPDATE: Okay, so I keep on trying to overclock it (fairly tame OCs), and running Furmark to see if there are any problems. Furmark keeps freezing up, my GPU fan go crazy and keeps spinning at max, and then my laptop emits load beeping. What's going on? I've tried compensating by increasing voltage but it keeps on doing it. Other than that, there are times while I'm benchmarking that I'll notice my FPS go into the gutter, only to check and see that somehow my laptop is now running on battery (even though it's plugged in - I have to manually unplug and replug the AC back into the socket). Apparently overvolting to say 1.2 V forces my laptop to run on battery power. I've searched Google, nothing. This is so weird...