Overclocking a 2500k using

so i finally decided to oc my 2500k only to 4.0 ghz and i had it auto @ 1.3v. at the time i wasnt sure how to set it my self so i roled with it, but now i since changed it to the lowest vcore i could.

at the start i was able to get a -.1 offset but it wouldnt throttle down, it was stuck at a constant 4.0 ghz. since fixing that, making it go to 1.6 when idle, it was too low of an offset, unable to keep 1.6 stable (via hwmonitor it needs like .87?) so i had to boost it up to -.8 just to boot

my question is shouldnt a .02 boost be able to atleast attain 4.1 or 4.2? if i kick it up it just bsod'd on starting windows

its possible i could have gone lower than -.1 but i noticed the constant voltage issue and fixed that instead of seeing how low i could go

Last edit: 2012-08-19 15:18:18

Medrea August 19 2012 15:20. Posts 9999

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Just leave Vcore on auto and change the multiplier to 40. No need to touch voltage for sandy bridge for that kind of overclock if its stable (prime95)

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Syngelic United States. August 19 2012 15:21. Posts 78

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i was just curious to how low i could go, 1.3 auto seems way too high for just a .3 ghz boost

Last edit: 2012-08-19 15:24:49

Medrea August 19 2012 15:27. Posts 9999

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.7 ghz boost. The turbo should set itself to 4.4

You dont really need to go lower. CPU power is on its own rail for the most part, and Sandy bridge is pretty low cost on overhead as it is. I dont really see mine going above 77W very often.

Last edit: 2012-08-19 15:29:19

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Syngelic United States. August 19 2012 15:28. Posts 78

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o.0 why would it do that if i have my multiplier at x40?

phar United States. August 19 2012 15:30. Posts 566

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If your temps seem ok, you don't really have to tweak it.

If you REALLY REALLY REALLY want to bring your temps down because it bothers you (or because you run your computer in an oven-like environment), then yes, you can drop the offset. Unfortunately every chip is different, so nobody can tell you exactly how low is safe. You can do something like this to test:

1) Bump to X multiplier, whatever you want
2) Run prime95 for a long ass time, verify that its stable
3) drop offest one increment

Repeat 2 and 3 until #2 doesn't work properly.

4) bring offset back to last stable

Do note that you can't drop it down too low, because it has to be stable on the other side as well.

Last edit: 2012-08-19 15:32:30

Who after all is today speaking about the destruction of the Armenians?

Medrea August 19 2012 15:30. Posts 9999

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Base core speed of 3.3 ghz. So multiplier defaults to 33. Changing multiplier from 33 to 40 makes base core speed of 4.0 ghz. Boost speed is 400mhz higher than base speed.

I'm not gonna even talk about voltage because if you have to ask someone for assistance you shouldnt be doing it anyway.

Last edit: 2012-08-19 15:31:10

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Syngelic United States. August 19 2012 15:33. Posts 78

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@phar the question isnt really how to overclock using offset, its me using it and more so questioning my results. my goal was to hit 4.0 ghz but since the offset was too low to start (the run the 1.6 ghz as idle) i had to increase the voltage. im asking the offset i add to increase should be enough to have something higher than 4.0 (i.e 4.1 or 4.2) or is my chip that shitty? if seen others say they average 4.1 ghz @ 1.17v and im peaking at 1.21

Syngelic United States. August 19 2012 15:34. Posts 78

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im not boosting the base im boosting the turbo which is 3.7... in no way could i adjust the base, and using cpu-z it never even goes to 3.3 ghz,.

phar United States. August 19 2012 15:35. Posts 566

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It's fine. 0.04 difference when you're < 1.4/1.5 is not the end of the world. If you have a decent cooler you can probably even do 1.4 and not really care (not recommending that you should, just that it wouldn't make a huge difference).

If you figured out how to get it stable when you start up (on the low end) and you're seeing reasonable temperatures under load, and it doesn't do funky shit during prime95, you're probably ok.

Last edit: 2012-08-19 15:36:35

Who after all is today speaking about the destruction of the Armenians?

Medrea August 19 2012 15:37. Posts 9999

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I dont have an ASUS motherboard so I dont know for sure what they call it. Should definitely be able to overclock its base.

In CPU-z you are probably seeing its power saving mode where it drops to 1.5ghz or so. Have something going on in the background to see whats going on.

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Medrea August 19 2012 15:40. Posts 9999

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Just to clarify. When I use CPU-z it shows core speed of 1596. Then after I wake it up. It shows 4 (3991) ghz with multiplier of 40.

Last edit: 2012-08-19 15:41:55

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Syngelic United States. August 19 2012 15:41. Posts 78

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@medrea yeah i understand, ill say this for the 3rd time, the offset adjusts both the power saving and the turbo so i was forced to raise the offset because it was too low to boot with power saving on (which i want on) so i had to add extra voltage to the 4.0 ghz for no reason but that. SOO the question was with the additional voltagte needed to run in power saving (like .87v) it bumped the turbo voltage up to 1.21 from 1.19 where it was stable prior (and prolly could have gone lower) im just interested in why with the extra voltage needed for 1.6 that i cant get it to 4.1-2 on that same voltage

phar United States. August 19 2012 15:42. Posts 566

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I'm not 100% clear on what OP was saying. I assumed he meant that he dropped the offset so low that it was not stable on startup. That can happen. In particular, if you're doing aggressive low offsets, you need to check the voltage when you [b]first start up[b/]. When the CPU drops itself down to 1.whateverGHz (1.5, 1.6, whatever), it needs to have enough voltage to be stable. Maybe 1.0, maybe 9.8, maybe 1.1, really depends on the CPU.

Edit: ok yes, I see your above post, exactly.

Last edit: 2012-08-19 15:42:20

Who after all is today speaking about the destruction of the Armenians?

Syngelic United States. August 19 2012 15:42. Posts 78

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same for me, its either the power saving 1.6 or 4.0 with turbo

phar United States. August 19 2012 15:44. Posts 566

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To answer your question, why do you need extra voltage when you're at 1.6GHz?

Because a CPU needs a certain amount of voltage to operate. It's difficult to get into specifics if you have not studied semiconductors. You need a certain amount of voltage to be able to drop a signal at a fast enough rate to execute instructions at a <1ns clock. That amount depends on the material used and how good the specific die your CPU was cut out of is. It varies from chip to chip.

And take everything I say with a grain of salt because I'm by no means an expert on semiconductors, and I'm massively paraphrasing here.

Last edit: 2012-08-19 15:44:48

Who after all is today speaking about the destruction of the Armenians?

Medrea August 19 2012 15:47. Posts 9999

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On August 19 2012 15:42 Syngelic wrote:
same for me, its either the power saving 1.6 or 4.0 with turbo

Thats base, not turbo.

Test in prime 95 to be sure though. After it hits all cores check in CPU-z. That number will be your base clock speed. Turbo is something this generation does for single threaded tasks only and I dont think its declared in CPU-z.

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Syngelic United States. August 19 2012 15:47. Posts 78

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@phar i have what you said as an "aggresively low offset" i was curios to how low i could get the 4.0 ghz just as kind of a learning expereince sort of thing. apparently the offset was too little to handle the 1.6 (it was at like .65v with the same offset) and booting takes .85v or so for my chip so i had to raise it to boot, the 4.0 is perfectly stable at a much lower voltage

Last edit: 2012-08-19 15:48:22

phar United States. August 19 2012 15:47. Posts 566

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Anyways, if you're stable at low clocks, and stable at high clocks, and your temps look ok, don't sweat it. Not worth the headache, especially for a relatively conservative overclock.

Ah, as a learning experience. Well, you only have so many knobs you can control. It sounds like you've already fully tested your specific CPU.

Last edit: 2012-08-19 15:49:55

Who after all is today speaking about the destruction of the Armenians?

Syngelic United States. August 19 2012 15:49. Posts 78

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@medrea in the asus bios (atleast on my shitty board) there is only a displayed "turbo clock speed" so im sure that its the boost rather than the base

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