Undervolting and Overclocking the i7 3770K: Success ?

Discussion in 'CPUs and Overclocking' started by 1b0b1, Jan 14, 2013.

  1. 1b0b1

    1b0b1 Member

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    So I was able to overclock my cpu using a 43 multiplier and a negative offset (-0.060v) on my asrock z77 extreme4 with a level 2 llc (second highest).

    My voltage as shown on cpu-z reached a minimum of 0.792 on idle and a maximum of 1.200 when stressed completely using prime95.

    Temperatures ranges between 20c~35c (only 1 or 2 cores go above 30's) on idle and 50c~72c when stressed (all cores). During gaming (BF3 ultra settings, for 1~ 2 hours), it was in the med-high 60's (all cores).

    The stress test done was only for like 30~40 minutes and the idle test was for like 10 minutes. I KNOW that this is not enough at all but I am planning to do the real tests soon.

    Until now, I haven't get any BSOD during boot due to the low voltage and the stressing temperatures are acceptable considering that I am using a CM hyper 212 evo.

    What do you think ?
     
    #1 1b0b1, Jan 14, 2013
    Last edited: Jan 14, 2013
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  3. coffeejunkee

    coffeejunkee Golden Member

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    Well, even though you use a negative offset you're not really undervolting. Depending on cpu stock voltage is somewhere around 1.060 so 1.200 is quite a bit more. Using LLC also bumps up the vcore a lot. I would try without LLC and use about +0.045 instead.

    Apart from that my personal experience is that Prime95 or Linx is pretty useless for determining stability. Just tried again the other day, ran 20 runs Linx and 8+ hours Prime after that, only to get a ton of whea errors while playing BF free2play, not exactly the most demanding game. Had to bump up the offset another 3 notches.
     
  4. 1b0b1

    1b0b1 Member

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    Well, on asrock mobos, you can't simply turn off the llc. The only thing you could do is to set it on level 5 which is the least compensation level.

    On the other hand, every time I set the voltage to a positive value with a medium-low llc, my cores temperatures rises to high 70's.
     
  5. Termie

    Termie Diamond Member

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    Yeah, 1.2v is actually a significant overvolt, and is being triggered by the LLC. Your BF3 temps prove that: they are quite high. Your idle voltage is below stock, which shows that your negative offset is working, but it's being outweighed by the LLC at load.

    Anyway, you might be able to hit 4.3 with totally stock voltage. I assume that would be LLC level 5 from your post above. The voltage should be around 1.16.
     
  6. Saffron

    Saffron Member

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  7. 1b0b1

    1b0b1 Member

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    Guys, I was mistaken, I actually undervolted using the offset -0.060, which is even better. Anyways, I will try to roll back to stock voltage and only change the multiplier, we'll see how it goes. Thanks for the suggestions :)
     
  8. 1b0b1

    1b0b1 Member

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    Alright, so i loaded the bios defaults and set the multiplier to 43 and didn't touch anything. LLC & Vcore were set on auto.

    CPU-Z:
    Minimum Vcore spotted: 0.848v
    Maximum Vcore spotted: 1.264v

    Realtemp:

    All cores temperature during the prime95 test: 70~76 and of course, they will increase incrementally.

    What do you think ?
     
  9. Termie

    Termie Diamond Member

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    You should read the vcore under sustained load with all cores maxed. I would be surprised if it's 1.264v at stock. That would be very high. I assume that's just a turbo voltage applied to one core. Then again, it could be that this is the stock voltage applied by AsRock, which would make sense given that you had a -.06v offset and hit 1.2v before. Still, I'd double-check that, and definitely don't run it that high.

    The .848v idle voltage looks to be about what stock should be, if not a little lower than average.

    What concerns me if the stock voltage really is 1.264v is that you won't be able to run a low enough negative offset to get that into a proper range without potentially causing your idle voltage to drop to low for stability. I don't believe you can go much below .75v and stay stable at idle. Still, that would allow a -0.1v offset (which you might try assuming your default voltage really is 1.264v).
     
    #8 Termie, Jan 14, 2013
    Last edited: Jan 14, 2013
  10. 1b0b1

    1b0b1 Member

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    0.848v is on idle and 1.264v is happening right now, with the prime95 test during the maximum heat test. Sorry if I didn't make myself clear in the previous post.
     
  11. Termie

    Termie Diamond Member

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    Ok, see my comments in the post above - that default voltage is very high. Perhaps there are some other gurus that can chime in on whether that could have something to do with the CPU itself, but I'm assuming it's just AsRock overcompensating on the voltage to guarantee stability.

    I'd try a negative -.1v offset (1.164v) and see if it can hold stable at 4.3v.
     
  12. 1b0b1

    1b0b1 Member

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    I will start using the negative offset, should I keep the LLC on auto ?
     
  13. 1b0b1

    1b0b1 Member

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    I think you got me wrong, the voltage on idle was 0.848. I am pretty sure that this is not very high, in fact, it is an ideal voltage.

    When I ran the prime test, the maximum voltage spotted was 1.264v.

    Are we synchronized now ? :p
     
  14. Termie

    Termie Diamond Member

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    I'd start with LLC on auto. In my experience, that will use the lowest level, but it may be different on your motherboard.
     
  15. 1b0b1

    1b0b1 Member

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    If I am not mistaken, on the motherboard it was mentioned that the LLC level 1 was selected, which is the highest available, even though I picked the auto option is set.
     
  16. Termie

    Termie Diamond Member

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    I don't know specifics on your motherboard. There happens to be a very detailed thread on it, though, so you should check that out for answers: http://forums.anandtech.com/showthread.php?t=2244331
     
  17. 1b0b1

    1b0b1 Member

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    multiplier: 43
    Set the offset to: -0.015v
    LLC: auto (LLC1 [highest available] was selected by the mobo)

    cpu-z:

    idle: 0.832 minimum spotted
    fully stressed with prime95: 1.248v [although it reached 1.256v for half a second]

    temps on idle: 21~32
    temps while being fully stressed: all cores started at 65 and now they are on mid 70's
     
  18. Idontcare

    Idontcare Elite Member

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    Before I lapped or delidded my 3770k, here is what I was getting with an NH-D14. I'd expect the temps (and volts) to be slightly higher with the hyper 212, but I would't expect it to end up being much higher.

    [​IMG]

    Your voltages seem rather high for the clockspeeds you are shooting for.
     
  19. 1b0b1

    1b0b1 Member

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    Did you use offset or fixed voltage ? And what are the llc settings ?
     
  20. Idontcare

    Idontcare Elite Member

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    Those are manual voltages measured with a voltmeter while running LinX.
     
  21. 1b0b1

    1b0b1 Member

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    I can try the same, but what about the other settings, turbo volt ? llc ? PLL ? anything changed ? or just the multiplier and the fixed voltage
     
  22. Idontcare

    Idontcare Elite Member

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    I left everything to default BIOS settings except that I set "PLL Overvolt" to "enable".

    LLC for me was on an ASUS mobo so that is not relevant, what is relevant is the net target Vcore under load. You shouldn't need so much Vcore unless your processor is just one of those that needs a lot to be stable.

    The challenge for you, I suspect, is that you are running a relatively mild OC (4.2-4.5 is "mild") and because of that your offset voltage can be a large negative value...but that makes your system unstable when it is not loaded (idle voltages end up too low).

    I had the same issues using offset voltage. Negative offset voltage works but you can't go too big on the value, otherwise you find out your rig is stable when fully loaded but has issues when it is less than fully loaded.
     
  23. 1b0b1

    1b0b1 Member

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    Alright, now my Vcore is set to fixed: 1.120v and the multiplier on 43. Everything else is on auto.

    Now i am running the stress test, maximum vcore spotted: 1.128v and the temperatures started at high 50's and now 59~64..

    I'll keep the test going on for some time and then try to lower the voltage to see my stable settings.

    On the other hands, will a fixed voltage shorten my cpu life time faster than offset ? taken into consideration that the fixed mode will throw voltage at the cpu all the time, regardless if it is on idle or fully stressed.
     
  24. Idontcare

    Idontcare Elite Member

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    Fixed voltage wouldn't be expected to reduce your processor's lifespan in a significant way. Academically speaking, sure, your chip will now only function for 9 yrs instead of 9.1yrs ;)

    Remember that when the chip is idle the voltage on the cores goes to zero because of power-gating.

    The alternative is that you boost your OC even more such that your negative offset is lessened and the system is no longer at risk of being unstable when lightly loaded or unloaded.

    Of course that comes with the tradeoff of lowering your chip's lifespan as well. So basically you just have to decide when and how you want to stick it to your processor :p
     
  25. Termie

    Termie Diamond Member

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    1.12v seems like a reasonable voltage at 4.3GHz - in fact, it's fairly low.

    As for the issue of manual vs. offset, you'll be using far more power at idle with manual voltage (on the order of 20w more), but it will not reduce the lifespan of the CPU significantly, as it's still below what would be considered standard voltage at load, and the CPU should be designed to tolerate that amount of voltage.

    That being said, I'd probably just aim for an offset of -0.1, which would put you at 1.16v load and .75v idle. It should be stable in both cases, and you can even push the overclock a bit higher - perhaps 4.4 will be stable with 1.16v.

    If you haven't already, you might want to post in the AsRock z77 Extreme 4 thread I linked - that default voltage does seem a bit high - perhaps a new BIOS would help.
     
  26. 1b0b1

    1b0b1 Member

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    Alright, after a 1 hour test (maximum heat) on Prime95, it seems that everything is good with the below settings applied:

    multiplier: 43
    Vcore: Fixed 1.120v
    Everything else including LLC: Auto

    Lowest vcore during idle: 1.104v
    Maximum vcore during stressing: 1.128v
    Temperature on idle: 23~35
    Tepmerature while fully stressed: mid 60's, mainly 63,64,65

    I think this is a good OC... any comments ?
     
    #25 1b0b1, Jan 14, 2013
    Last edited: Jan 14, 2013