Go for it and post me your results please, you got me curious now haha. With your temps where they are I think you can do it.
That's 93c on the Intel burn test, I bet your gaming temps are probably 70c or a little lower which is fine.
Nvidia has the voltage locked, no matter what you set it to it won't go any higher than what it's locked at, mine are locked at 1.175v. The only way to raise the voltage is with a vbios mod and I don't recommend doing that.
1300MHz is pretty good on the core I can only get 1241MHz out of mine.
It might be best to reset to defaults, run it for a bit and see if you still get crashes. It's probably instability somewhere with your ram, cpu or gpu.
You have plenty of power so I don't think it's your psu, do you have the 4 pin cpu power cable connected? It's not mandatory but when overclocking extreme you want to have it connected.
You could reset the bios to defaults and enable xmp and run it like that for a while to see if it's a ram issue, if it seems ok then your cpu or gpu overclock is unstable.