My i5 3750k, undervolted and stable at 4GHz

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MoreGooder

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A quick search of the forums leads me to believe that no one here is trying to overclock and undervolt their 3750k's.

Last weekend, I upgraded my mobo, ram and processor from an old DFI/Q9550 setup. I know that my needs don't require pushing the processor to the limit, so I decided to undervolt my CPU to keep things cool and decrease my electrical bill impact a tiny amount. My original, and purely simple minded goal was to match my old processor's 3.2 GHz overclocked rate, but I was pleasantly surprised to see that I can run it stable at 4GHz. Actually, it ran several rounds of IntelBurnTest just fine at 4.1GHz too, but I figure why push it even further than necessary. (Yeah, I know, not really going to save the planet or anything like that).

I'm rock solid stable running x40 with a -.14 cpu voltage offset. At full load, the CPU voltage peaks at 1.138v. I'm watercoold, with an Apoge HD, and it peaks at 70C running IntelBurnTest.

All of that testing only took three hours to accomplish. I think if I had an entire weekend to devote to this adventure, I could stretch the overclock+undervolt even further.

I see so many people trying to hit 5GHz on the forums, delidding and so on. I hope my experience inspires people to see how much they can squeeze from their processors while actually decreasing voltage from stock recommended.
 
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Nice up grade. Does seem hot though. What TIM are you using? Mount may be bad. Poor IHS seating from factory is main reason many IB run so hot and reason many delid.
 
I'm using the TIM-MATE that came from Switech.

I'm surprised you think 70C is hot. TMax is 105 on IB, is it not?

Oh, and after posting this, I dropped PLL to 1.66. I'm now at 68C max. Idle is 34C average across the four cores. Core 4 is always the hottest, so perhaps that's a good indication that the IHS is not correctly seated by Intel.

Thanks for the feedback though.
 
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I think you can go alot lower on the PLL. Have you tried lower on PLL?


MoreGooder said:
I'm surprised you think 70C is hot. TMax is 105 on IB, is it not?
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105C may be the TMax but running it that hot is crazy. 70c isn't that hot to run but for your low voltage settings and low over clock it is hot.
 
Here is 4GHZ Intel Burn Test Run on my water cooled delidded 3770k with Hyper Threading enabled.

Ambient temps 24C
1.09v on vcore, 1.5v PLL
TIM Coolaboratory Liquid Pro
Direct Die to water block mount. No IHS with DT Sniper water block.

http://valid.canardpc.com/2597882


4ghzlowvoltage3770IBT.jpg


Delidding is like magic.
 
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MoreGooder said:
I'm using the TIM-MATE that came from Switech.

I'm surprised you think 70C is hot. TMax is 105 on IB, is it not?

Oh, and after posting this, I dropped PLL to 1.66. I'm now at 68C max. Idle is 34C average across the four cores. Core 4 is always the hottest, so perhaps that's a good indication that the IHS is not correctly seated by Intel.

Thanks for the feedback though.
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Something is definitely amiss with those temps @ that speed/voltage level. I usually run 70-73 on my 3770K @ 4.8Ghz @ 1.272V, and my cpu produces way more heat then your 3570K. Again, as SonDa5 mentioned, if you are watercooling a 3570K with a custom loop and seeing temps that high, I would recommend getting some better TIM and remounting it, if not de-lidding it as we have.
 
My 3570K has multiplier 44 (4.4Ghz) and Vcore offset +0.04, everything else on Auto. Temps stay under 80, still much hotter than my Phenom II.
 
Ok, I took off the TIM-MATE from Swiftech and replaced it with Antec Formula 7, which according to my googling, requires 200 hours to fully cure.

Even with the fresh layor of Forumula 7, I'm seeing a drop of 2° C, and am now at 66C peak. I did, however, have go back to a -.16 offset, and 1.627 PLL because I started running into issues.
 
MoreGooder said:
Wow.... Thanks for posting that.

I shouldn't be seeing more than 53C at 4GHz according to what I see on that chart. I'll try a few more experiments, and re-seat my block yet again. This time, I'll use a smaller dab of TIM.

Thanks gents!
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That CPU in that review ran at much lower voltage than what yours is at. I think that CPU had a great IHS seating from the factory as well. If you get a great mount and your temps are still high you should consider delidding to fix it.
 
MoreGooder said:
Ok, I took off the TIM-MATE from Swiftech and replaced it with Antec Formula 7, which according to my googling, requires 200 hours to fully cure.

Even with the fresh layor of Forumula 7, I'm seeing a drop of 2° C, and am now at 66C peak. I did, however, have go back to a -.16 offset, and 1.627 PLL because I started running into issues.
Click to expand...

I am glad you have seen a little improvement, hopefully you will get some more once that TIM cures..I am not a big fan of it since they are others that perform better for the same price without a "cure" period, but if it was what you had, then work with it.

As far as your PLL voltage, don't worry, 1.627 is pretty decent compared to the "Auto" voltage of ~1.8-1.89V that most MB's set. I dropped mine from 1.89 down to 1.64 IIRC correctly, and it did reduce some temps. I tried to go lower, but noticed no further decrease in temps, so I left it there.
 
I'm with every one else your temps are high for that voltage. I'm at [email protected] on my 3750k. Granted I have a 9x140mm rad I only hit 68-70c. What kind of water cooling setup and block do you have? Those are lidded temps im really temped to delid.
 
I have serial loop: res, pump, rad, Apoge HD, pump, rad, GPU res.
Rads are Thermochill 120.3 to cool CPU, Thermochill 120.2 to cool GPU
DDR3.2 + Petras top for above pumps. Pressure and flow are very good, so I'm certain the IHS is the problem.
 
I did some experimenting with this on my 3570k last night, I got 4.0ghz down to 1.095v with 1.650v PLL, temps max out at 61*C with a CM V8. Pretty happy with the results, still pulls down 101 gflops in IBT.
 
So I messed with mine a little today. Was at [email protected] to see how low I could get the Voltage for 4.4ghz. Now I'm at 4.4ghz with only 1.216v. Now Folding doesn't break 49c on any core and Burn in test didn't break 60c. Think I'll stick with 4.4ghz .204v is a lot for just 300mghz. Plus a drop in temps of almost 15-20c.
 
ccityinstaller said:
Something is definitely amiss with those temps @ that speed/voltage level. I usually run 70-73 on my 3770K @ 4.8Ghz @ 1.272V, and my cpu produces way more heat then your 3570K. Again, as SonDa5 mentioned, if you are watercooling a 3570K with a custom loop and seeing temps that high, I would recommend getting some better TIM and remounting it, if not de-lidding it as we have.
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I don't think there's much wrong with his temps, a bit on the warm side considering the specs, but hardly alarming. I've been reading IB overclocking posts since before it was even released and I've never seen temps as low as yours without de-lidding.
 
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