Hi everybody,
Can someone explain how voltage control works, and in particular, how manual control differs from offset?
I understand that most "real life" overclockers prefer offset. This is because the voltage scales with the CPU speedstep and thus adjusts the voltage (and hence heat and power consumption) depending on CPU load. My system (the relevant parts of it) is: i7 2700k, Asus P8Z680 Deluxe/Gen3, 2xGTX 680, Noctua N-D14 cooler.
Here's my issue. I want a liveable system for general use as well as performance oriented tasks. I have overclocked the CPU to all four cores max turbo 4.84 GHz (103*47), in order to maximise performance when I need it. I prefer to just "set and forget" and use the same BIOS settings whether I'm gaming, working, browsing, video editing, transcoding, whatever.
I'd really like to use offset because this allows the voltage (and hence heat and power consumption) to scale with load. Under manual voltage control, voltage seems to adjust with load a bit, but in a much narrower range.
The problem is this. When using the offset mode, if I set it at "Auto - by CPU", it scales to a crazy voltage under load. When running Prime95 the voltage goes up to 1.6V (and the temperature goes up to 85 degrees). This is obviously far, far more than necessary and unacceptable for a Sandy Bridge CPU so I quickly shut it down. However, if I set the smallest negative offset of -0.005V, my computer blue screens on start up without fail.
There seems to be no offset voltage setting that will boot into Windows without blue screening, that doesn't also scale to an excessively high voltage under load.
I therefore seem to be stuck with manual control - I have set the manual voltage at 1.36V. This boots ok and seems to be stable under load with all 4 cores at 4.84 GHz. Under load, temperatures hover around 65 degrees, which is fine and the voltage increases to 1.392V. (The fact that it is stable at this voltage proves that my voltage scaling under offset mode is completely crazy and unnecessary).
So if manual control works, what's the problem? Well, as I write, the CPU voltage is 1.378V. I am not doing any background tasks, just writing this post. It works but is far more than necessary. I like to leave my computer idling for long periods of time, but at this voltage it's using far more power than necessary.
The solution would appear to be offset voltage control but with a sensible scaling factor. Is there something else in my BIOS settings that can affect the scaling factor? Eg Load Line Calibration? Or do I just have to accept that at my multiplier settings, I will never get offset voltage control to work?
Any help or insight much appreciated.
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