How do you determine where to start in Vcore Offset Mode for 2500K/2600Ks?

[MadScientist]

I've observed that when I set my 2500K to 4.6Ghz on my Asrock Z68 Extreme 4 MB using the auto turbo preset that it sets the offset voltage to +0.075V. I'm assuming it does this by setting the vcore and other parameters, i.e., Additional Turbo Voltage, by adding offset voltage to my CPUs VID to obtain a stable overclock.

On another forum someone stated that to set the vcore offset mode first determine a stable vcore for your specific CPU speed using the fixed vcore method and then subtract your VID from that to get your starting offset voltage.

Which VID, the idle or load VID at stock bios settings? According to CoreTemp V1.0, my stock VID at idle is 1.2360V and at stock load it's 1.2710V.

Edit: These VIDS were not at stock but at 3.4Ghz load due to my MB setting the multiplier to 34 at its default bios setting.

I found using the fixed vcore method that I need 1.330V (CPU-Z) to be stable at 4.6Ghz.
The auto turbo sets it a tad higher at 1.340V load, VID is 1.2610V idle, 1.4111V load.

I also found that setting the offset voltage to +0.075V with +0.027V additional turbo voltage, or +0.080V offset voltage, is stable at 4.6Ghz at LLC level 5.

So what would I subtract from what to get a start point for offset voltage?

 

[MadScientist]

Ok, I think I have the answer to this thanks to info posted by RussianSensation. Please correct me if I'm wrong.

Ok this part is a bit tricky:
CPU Vcore = what your CPU boots at 3.3ghz (its stock / out of the factory VID).
Dynamic VCore = what your CPU needs to get above 3.3ghz.

Enable CPU Vcore (Gigabyte's setting may be called "Normal") and set it to stock. Let's say yours is 1.220.
Now see the DVID setting? Add +0.160V (then 1.220V + 0.160V = 1.380V at load). If you were to add Dynamic VID as +0.200V, then your motherboard would aim for 1.420V at load (assuming your stock CPU VID was 1.220V). Makes sense?

OR To start, you can set VCORE to 1.38V right off the bat and see if this works. Later on you can just use 1.38Vcore - your CPU's stock VID + DVID setting adjustment (this is the "offset setting"). [So if we found out what VCore we needed, we could back into the required Dynamic DVID Vcore later).

I first had to make a few tweaks to my bios, disable spread spectrum to get the BCLK to 100.0Mhz, and set the multiplier to 33 manually. My MB when set to default in the bios overclocks it to a 34 mutiplier and sets the BCLK to 99.7Mhz.

My VIDs at stock settings are idle 1.1559V @1.60Ghz, vcore: 0.98V (CPU-Z); load 1.2460V @3.30Ghz, vcore: 1.176V (CPU-Z).

If I take the vcore I need to be stable at 4.60Ghz, 1.33V, and subtract the VID, 1.2460V, at stock load, 3.30Ghz, I get an offset voltage of 0.084V. Close to the +0.080V offset voltage setting I found to be stable at 4.60Ghz.

 

[Idontcare]

As you rightly noted, offset is usually computed by taking the delta of the VID versus applied Vcc at full load.

But be aware that the way the offset method works is that the offset is applied regardless the VID. So the same offset is in effect when your VID changes to a lower value when the chip goes idle such that the formula "Vcc = VID + offset" is always in effect.

This means your idle volts are higher than they would otherwise be, maybe not a problem, but it can be a problem if your offset is actually negative.

My cpu was applying too much voltage at 4.5GHz, the VID was calling for more voltage than was necessary. So I found the minimum voltage for IBT stability, applied the negative offset and was happy as a lamb.

That is until I found out that the negative offset was actually pushing my idle volts so low that the rig was locking up when the chip idled.

So you really do need to ensure the offset you select is an offset that leaves your rig stable at both its loaded and unloaded extremes.

With a positive offset I don't see this ever being a problem, it only should be a problem if you are using negative offsets.

 

[MadScientist]

Thanks for the additional info.

 

[BonzaiDuck]

Thanks for the additional info.

This could be an interesting thread. I see you guys are still tweaking after last year. Mad is still using that Z68 Asrock board.

These things mentioned are approximately what I did last year -- I took 20 legal-pages of notes. And I can't remember precisely all the details -- even for reviewing the notes. In fact -- I'd taken data -- not at stock settings -- but at otherwise stock settings with a 103 bCLK.

I'm guessing if I want to OC a tad more, I could simply start from my existing reference-point and tweak the Offset or "Extra Voltage Turbo."

 

[borisvodofsky]

Going up to 4.7ghz you'll need around 1.35 1.36

Going beyond that 48+ requires 1.39-1.42

This is synonymous on nearly EVERY chip sold today

talking sandy ofcourse