Trying to push BCLK on SNB

[Khenglish]

Do you guys know of any tricks to push BCLK overclocks higher? The reason I ask is because the CPU will ramp up to 1.35V VID starting at x34. The heat from this voltage is difficult to control in a laptop, and with the same voltage being run at 3.4GHz as 4.35GHz with both being stable, it's obvious that the voltage is very excessive. I've noticed that increasing multipliers causes an automatic voltage increase, but increasing the BCLK does not. So the idea is that I can effectively reduce the voltage at the same clock speeds by raising the BCLK and running lower multipliers.

There are no BIOS options to control voltage. XTU only allows positive voltage offsets, not negative. Disabling auto voltage control and setting fixed VIDs is not possible. The only options I see are VRM mods and raising the BCLK to lower voltage.

I have reduced the memory from 1866 to 1600, which lets me get to only 104MHz fully stable (100.5 at 1866). I have also set the SSD to SATA 2 instead of 3, but this offered no improvement.

I never get any calculation errors when running something like Prime95 when the BCLK is too high (unless memory is at 1866). The system just freezes. BCLK stability over 104MHz is inconsistent. Usually 105MHz or higher is an instant crash, but once 107MHz was stable for several minutes. Crashes will occur without load.

So any suggestions? What have you guys found to often be a BCLK limit culprit and how I can get around it? It'd be stupid to have to get an IVB just to get reasonable voltages.

System:

Unlocked SNB quad ES stepping 5 (similar to 2920xm)
Clevo P150EM with P170EM BIOS and modded ME FW for XTU support
GTX 680m
Samsung 840 Pro 256GB


Thanks for reading. Any suggestions would be appreciated.

[sin0822]

vcore helps, but in a laptop i don't think there is much you can do. SNB doesn't really like increased BCLK.

[Khenglish]

vcore helps, but in a laptop i don't think there is much you can do. SNB doesn't really like increased BCLK.

That's what I was afraid of hearing.

VRM schematics look unfriendly to modification (lack of resistors on voltage feedback loop). I guess I'll look at them some more to try to find something. So dumb that you can raise, but not lower voltage with XTU.

[Khenglish]

vcore helps, but in a laptop i don't think there is much you can do. SNB doesn't really like increased BCLK.

Just read though your guide. How big on an impact is VCCIO? I have the motherboard schematic so I should be able to raise it, but if I only get like .2% after all that work I will not be happy. Schematic says it's exactly 1.05V.