Trying to OC using "Offset" method for vCore with i7-870

Hi all,

I'm following lots of guides and info from forums to do my first oc, the method I want to follow somewhat is what others call "dynamic overclock" where you use a lot of the power saving features, although I personally want to skip out on c3 and c6.

So apparently one of the things that is necessary to get vCore to save power and lower heat in idle properly is to adjust vCore with Offset rather than setting a static voltage, this is easy enough. For example I initially set my offset to 0.125 so that in CPUz I ended up with ~1.35v at various loads so that I could check how my cooling would do with that kind of voltage, and at idle the core would drop to ~1v helping with power saving and heat, speedstep and c1e seem to bo working properly.

So far so good but the thing no guide or forum posts I found mentioned was what happens with the IMC (vtt), you can not use offset for this just a static voltage which I ended up setting to 1.32v just for the quick test I was doing.

I've read lots of times the vtt should be no more or less than 0.03-0.05v off from vCore, so what happens to the vtt when the cpu goes into a power saving state and drops vCore to ~1v, will vtt scale down also if it's set to a static voltage in BIOS? or does that rule only matter for load conditions?

Where did you read that vtt & vcore should be close to each other? I haven't read that in any of the guides I've found... tried a quick google search and couldn't find anything about it.

Check out the guid ein my signature...

The Vtt needs to be within .5 of your MEMORY voltage.

As far as the offset, I think that just prevents Vdrop. If that is correct, just use the regular voltage to overclock.

Welcome! And again, read the guide linked in my signaure.

Earthdog: The 'offset' he is talking about is not the same as the offset you are talking about.

Some motherboards allow setting vcore by an offset from the base, as opposed to putting in a fixed number.

E.g., my motherboard considers vcore base to be 1.15V.

I get the exact same voltage if I do:
Offset mode: .05V

or
Direct mode: 1.2V


The difference is that in the direct mode (I made that name up--I forget what the non-offset mode is called), the base voltage cannot be changed by power saving features, whereas in the offset mode, it can.

(EDIT: Earthdog--check out page 4 of the 3-step bloomfield guide you link in your sig, under the CPU Vcore section--it discusses this)

I'll have to assume that it's ok then, none of the guides mention it but other overclockers repeat that same rule (.03v-.05v difference between vtt and vcore) so it's gotta be coming from somewhere.. it's possible that it's a rule from a few generations back and some still go by it? I don't know but I've seen it a few times in i5/i7 oc threads, however since it's not very often that it gets mentioned and I want to use the "Offset" method of adjusting vCore I'll ignore that rulefor now unless someone says otherwise.

The 0.5v between vtt and vdimm I know but it's a lot easier to keep within those parameters, the other one had me stumped.

Later when I have time I'll dig up some references on that, right now I'm running late picking up the wife, I may not finish my OC because I'll be dead soon

p.s. Earthdog: Thanks, I know that guide, even though I'm doing some things differently I'm still learning things from it, it's a great guide