I've been playing with it as you described for more than 2 weeks now. 
I started with the same angle the others are in (17-18 min and 25 min). Then I've found this post (see below). The picture shows the factory Vcore. The NewPac is the same in this regard as the F, I suppose, therfore I was playing in this area to hit the sweet spot without success until now. I have a feeling as the miner would need a memory reset or so and then the problem would be solved.
I can't load the image right now, but please try dialing all the way back from what you set it to (apparently around 20-25 min) back to like 5 min and try to go from there. I started with the same angle the others are in (17-18 min and 25 min). Then I've found this post (see below). The picture shows the factory Vcore. The NewPac is the same in this regard as the F, I suppose, therfore I was playing in this area to hit the sweet spot without success until now. I have a feeling as the miner would need a memory reset or so and then the problem would be solved. These miners have no memory, so there's nothing to reset. They are extremely simple devices, consisting of essentially:
- Crystal[/li
- ASIC
- FTDI chip
- Counter chip
- Buck converter circuit (some passive components and a buck controller IC)
I've tought about the heat too, but if it was an issue why are the others performing well?! ...even at 500 MHz? I'm afraid if I set a higher MHz at this stick and turns out to be the heat the real problem, I'm melting down the whole stick in a blink of an eye...Higher MHz doesn't really make it draw more power; your vcore screw is what really mostly makes the difference. Please try dialing all the way back and retry from there.Anyway, I won't give up. I'm still trying to find the right position, but it's getting to be really annoying to waste so much time on this.I thought so too; had a very bitchy stick (it needed just the right start frequency and vcore), but then I remembered the first page of this thread:It is also made for overclocking. Hot-rod overclocking.
It's supposed to be like this..