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Offset vs Fixed Vcore? (2600K OCing)

post #1 of 9
Thread Starter 
I just recently noticed "Offset mode" in my Vcore tab in uefi/bios.
Obviously it's a great feature whatever it does. Cause now I can even lower my vcore at previous clocks.

So my question is. What does "offset" do exactly? I see no difference in voltages in either cpu-z nor hwmonitor when i i.e set it to -0.020 and +0.020. Or am I completelly blind?

Another question.
I have started to play with the blck settings, raising it from 100 to 103.5. It's only for testing but does it do any real long-term damage?

Cause I tried another prime95 run for about 1 hour with the blend mode. And it didn't crash or anything.

The overclock with the blck setting to 103.5 http://valid.canardpc.com/show_oc.php?id=1786068
It gave me 4968Mhz at only 1.36V. And that was with HT enabled :S

Short version: is it safe to overclock with "offset" to achive higher clocks with a lower voltage? at idle it also drops my voltage ALOT (0.8 or something). And is it safe to use blck at around 103-104?

Please have an open mind regarding my noobness ^_^
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post #2 of 9
With regards to your voltage dropping, are you using some type of load line control or vdrop? I was having an issue with that and it fixed it.
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post #3 of 9
Thread Starter 
I have been using "fixed vcore" at all times until today. Hmm do you mean "load line calibration"? Its set to auto so I'm not sure really. There is level 1 to 5 if i choose to select a value.

Edit: I'm not really having a problem with my voltages. I'm just curious what offset does that fixed vcore doesn't. Cause obviously its a more effective way of overclocking. But that's just because I run at a lower voltage. But which is best in the long run? Having a voltage going up and down all the time depending on different load, or having it fixed?
Edited by XrOo - 4/24/11 at 4:40pm
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post #4 of 9
I've only recently ever used offset, I believe this relates to the standarized VCore levels that the mobo sets when you set your clockspeed to something (using some technical term that I don't recall). So when you offset by .xxx it adds or subtracts that quantity to the value, instead of manually setting the voltage which pegs it at that level constantly (why you get lower voltages at idle, using all the nice power saving options that come with chips these days).

Why you may not notice a difference between +.02 and -.02 might be because of the size of the offset in comparison to voltage "wobble". You don't get a truly fixed voltage, but rather your PSU/mobos best approximation of averaging to that value.

As for BClk, it's fine. People have been BClk OCing in much much higher amounts for a long time. It's usually not going to give you anything you couldn't get without it, except for a slightly more fine granulation on clock speed adjustment.

Hope that helps.

Oh wanted to EDIT a PS, 5GHz @ 1.36V is pretty darned nice. Grats on a nice chip if it's truly stable (a 1Hr blend isn't quite enough for most people wink.gif )
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post #5 of 9
Thread Starter 
ocpokey. Would you recommend a fixed vcore or would offset mode be just the same? I'm obsessed with the idea that having a frequently changing vcore is dangerous. When it may not be?
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post #6 of 9
Running with offset vcore is my prefered method for milder daily overclocks. I've been using it with no problems.
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post #7 of 9
I don't know if it works like it does in X58, but in my platform the "healthiest" way to overclock is to set and Offset value while disabling Load Line Calibration.

Offset voltage is a value added to the base voltage of your CPU. If at stock you have 1.1V, and you set +0.2 to the offset voltage, you are stating that the maximum voltage is going to be 1.3

Load Line Calibration forces the voltage you set in the BIOS through the chip, and gets rid of Vdroop. Vdroop is a drop on voltage which follows Intel specifications to avoid damaging the CPU. WITHOUT LLC, when you set 1.35V on the BIOS, while you stress test the chip, voltage might drop to 1.3 - 1.25 V. When the test stops it will go back up. So Vdroop only is enabled while your CPU is under stress. This means you will have a larger voltage when idle than while doing work.

Therefore you need a method of having a lower voltage when you CPU is idling. Enter C1E. With this feature, the CPU lowers it's multiplier when it`s idling, but also lowers the voltage! This is why Offset voltage is useful. It dynamically adjusts the clock AND voltage to what the chip needs.

Without Offset you CPU doesn't know what maximum and minimum voltage you want. It will just stay at the same voltage the whole time, while idling and while doing work. If the voltage is not very high, the degradation shouldn't be substantial, but it's always nice having lower voltage when you don't need alot of power. Why would you want to use 1.45V when browsing the web when you could do the same at 1.1?

Also, this inderectly lowers the temps a bit. With lower voltages the chip is less hot, but when it idles it also underclocks and the temperature difference is very noticable.

If you want to know more about Vdroop, check out this post. I hope this isnt tltrt tongue.gif
post #8 of 9
Thread Starter 
WOW! Now that was a lot of information. smile.gif
What I still dont understand though is that why is it possible to overclock higher with offset?

I.e, http://valid.canardpc.com/show_oc.php?id=1786068 <- 4.96HT @ 1.36Vcore. With a +0.020 Offset. It worked stable for about 1 hour until I stopped.

Now here's the funny part. If i set a fixed vcore at 1.36 at the same clocks (nothing change except vcore) it just either freezes in windows and reboots or gives me a BSOD error.

Same thing with my 5.0 try.
http://valid.canardpc.com/show_oc.php?id=1786141 > 5.0HT @ 1.368Vcore.

How can it run "stable" at lower voltages with offset and not with a fixed vcore?
Elsewise everything is at it was. Speedstep is on, c1e and all that other junk.

Highest temp was ~72C on Core2. So I thought that sooner or later it would burn up.
Seems like the chip can get high clocks at low voltages, but it still runs hot. Either that, or my cooling sucks big time.

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post #9 of 9
I need to leave now so I can't search, but CPU-Z is not extremely accurate for voltage reading, so maybe +0.02 is actually higher than 1.36, but CPU-Z doesn't detect the difference. The only way to know the actual voltage is with a well calibrated multimeter.

This is the only thing that pops to mind...

EDIT:

Quote:
Originally Posted by evolart;12998287 
Offset mode gives you more stability at lower maximum voltages. When settings the voltage change it from fixed to offset. You will often get lower stable voltages than with fixed, that alone is a great reason to do it. The other reason offset is sweet is that it doesn't keep your processor at a set voltage. This allows you to save power, heat, and add longer life to your processor. Just start at +0.005V and work your way up. I was able to get it working at -0.010V (which when under full load was 1.23V) but it wasn't stable enough.

For my setup +0.005V = 1.28V under full load. ph34r2.gif


I found this post. It seems that Offset actually makes the overclock more stable. I dind't read the whole thread but if more users are experiencing the same, i guess it's absolutelly normal.
Edited by hugo19941994 - 4/26/11 at 9:30am
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