# SandyBridge 2600K Overclocking - screens, hints and selection



## SoF (Jan 13, 2011)

Hi all,

just thought I share my OC experience and things I found out on my new 2600K with you guys so that you can see what SandyB1tch is capable of doing even without DICE or LN2.
*
SuperPi 1m @5500 MHZ aircooled*






*
SuperPi 1m @5588 MHZ singlestage *(my absolut max is ~5590-5595 but that is sometimes really hard to pass)






*Pifast @5588 MHZ 13.23s*






*Wprime32m @5589MHZ*






Also in 3D that chip can do nice things - specially the good old 3D Mark 2001 shines again  
*
01 110k*





*03 125k* 




*
05 49380*





*
system single stage cooled:*





*
Now some things you should keep in mind when benching SandyBridge:*

- max Vcore under Air/Water *single threaded benchmarks: 1.6V* (short term, risky!) 
- max Vcore under Air with *4C/8T 1.4V - 1.45V* I would say (everything else will get your chip past 70°C often)
- max Vcore under *Water with 4C/8T 1.5V* I would say (everything else will get your chip past 70°C often)
-* Vdimm 1.65V is fine*, also 1.7V didn't fried the chip under Air yet
- if you have problems running higher RAM speed or better timings try adjusting VCCSA between 1V and 1.1V - that helped me quite remarkable getting 1866 and 2133 running
- another hint for RAM - try using high timings when having issues with high memspeed, specially TRCD and TREF that helped me specially when going cold
- *lower your Vpll!* 1.725V seems to run better compared to the default 1.8V when overclocking past 5
- make sure to have a board+bios with "internall PLL overvoltage" option - without it you will be surely limited to 47-5000 MHZ 

*At last some things about how to find the real "golden eggs":*

Core i7 2600K 5 pieces

*all batch: L040B165
*
Testing without internal PLL overvoltage:
1x 4700 
1x ~4888
3x 5000 

One of them wanted to boot 51x100 but couldn't fully manage it

out of thoose 3x5000 with pll overvoltage

1x 5537 MHZ 32m
1x 5555 MHZ 32m
1x 5588 MHZ 32m
___________________________

Then we have a newer batch now coming which already did multiple 56x100 with pll overvoltage on water and air CPUz 

*Batch: L040B307 *

56x100 1.572V*

--> good chips boot 5 GHZ 1.4V or less Vcore without PLL overvoltage option enabled and will go past 5.5 GHZ on air for CPUz validation with PLL overvoltage and below 1.6V Vcore *

That's it for the moment 

regards
SoF


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## Konceptz (Jan 13, 2011)

Thank you sir!


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## overclocking101 (Jan 13, 2011)

wow, these could seriously be 6-6.5ghz chips if the cpu would allow it!


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## SoF (Jan 13, 2011)

overclocking101 said:


> wow, these could seriously be 6-6.5ghz chips if the cpu would allow it!



I still try to get more information about that "internal pll voltage" function. actually nobody seems to know exactly what it does but it is the most important voltage for overclocking beside vcore. I would like to know what that voltage is with and without enabling this function, but there is no way to measure (yet?). 

the chips don't scale with cold I can say: maybe you need 0.05V less vcore with single stage compared to air or water but it doesn't help in steps of 400 or 500 MHZ like we are used to.


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## erocker (Jan 13, 2011)

Internal PLL voltage is the Internal Phase Locked Loop. Basically, it controls the alignment of the CPU phases, QPI phases and other clock generators on the board. Adjusting the voltage of the PLL is necessary when "highly" overclocking (depends on the quality of the board) your other board components to keep the phases and clocks aligned and stable.



SoF said:


> but there is no way to measure (yet?).



Best way to tell that it is working is to check the voltage and clocks of the other components. If you think things are somewhat stable there but get fluctuations, that's where PLL comes in. Raise OLL a bit and see if the fluctuations tighten up or go away.


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## PopcornMachine (Jan 13, 2011)

Thanks for the very interesting post.


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## SoF (Jan 13, 2011)

Konceptz said:


> Thank you sir!





PopcornMachine said:


> Thanks for the very interesting post.



Thanks!



erocker said:


> Internal PLL voltage is the Internal Phase Locked Loop. Basically, it controls the alignment of the CPU phases, QPI phases and other clock generators on the board. *Adjusting* the voltage of the PLL is necessary when overclocking your other board components to keep the phases and clocks aligned and stable.



Thanks for bringing some light into that  It seems not to be the same as the PLL you can adjust for the CPU (what confused me first). I really hope some time later we can manually adjust it somehow. I've seen a screenshot of that AMI Bios editor (I whish I had that but heard the SDK is like 800$ *eek*) where this option can be adjusted with multiple options, so my hope is on this option to get even more out of SandyBridge-CPUs. They have some room left for sure 



erocker said:


> Best way to tell that it is working is to check the voltage and clocks of the other components. If you think things are somewhat stable there but get fluctuations, that's where PLL comes in. Raise OLL a bit and see if the fluctuations tighten up or go away.



no there seems to be no fluctuation in any voltage (cpu pll, vcore, vdimm checked) - apart from that I am still having a hard time understanding what changes when you only turn on that option. I mean the chip will fly with the same voltages like 500 MHZ higher instantly flawelessly. Hardly can remember seeing a voltage having so much effect on the OC at once before.


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## PolRoger (Jan 14, 2011)

Thanks the o.c. tips!! and for confirming L040B165 and L040B307... I've been searching batchs and those two were already on my short list.


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