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i5 750 Lynnfield overclocking


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I got a bit more rencent CPU - i5 750 Lynnfield with somewhat decent mainboard (MSI P55A-GD55 - Intel P55 chipset socket 1156 mainboard rev. 2.1) and since I was not overclocking such CPU ever, I would like to get some tips from guys that are sucesfull and know, what these chips want and how to get them to run fastest.


The basic specs of my i5 750 Lynnfield are 2.66GHz with turbo 3.2GHz, witch looks slow to me.


About the overclock - well, I just at first used the OC genie, but that won't get me far (3GHz base clock, IIRC 3.4GHz turbo).


First I just copied what the OC genie do, but then I get into some manual tweaking. OC genie pushed Vcore hard:

Vcore +0.278V

VTT - 1.314V

Vdram - 1.701V


I find out, that with Vcore just mere 1.112V it do 3578MHz stable:




However I hit the wall with 3.6GHz cannot run stable - it always freeze, even with much higher Vcore, so the problem must be somewhere alse.


Bumping the Bus speed from 210 to 215 resulting in 3663MHz, witch always freeze the machine during tests, even with lowered the memory speed to make sure, that this is NOT because of memory cannot cope with the speed, especially with tightened timings 9-9-9-18 ;) CPU-Z validation can be made, tough:



But it is not stable. I overheard the VTT might need a bit more "love", but I figured that I better ask fellow overclockers first :D Currently there is just a suxxking default intel noisy heatsink, so it is just for the testing:


RHRSoul_PC.jpg RHRSoul_PC2.jpg RHRSoul_PC3.jpg




Futhermore I would like to ask about some bios settings (features of the i5, for example), witch are suggested to be disabled/enabled in order to get maximum speed. IIRC one czech testing server always disable virtualization, so that probably should be a good start. Of course disabling the Spread Spectrum to get overclocking going, but there are far more options I'm interesed about, like:


Intel EIST - IMHO off, because this is not NTB that need baterry support and I want always full clock

Intel C-State - IMHO off, because conserving the energy is not the speed goal

C State package limit Setting - IMHO off, because I did not want any regulations

C1E Support - IMHO off, because sky is the limit and I don't want any other limits there

OverSpeed Protection - IMHO off, even MSI recommend that for OC

(between these CPU features are in manual mentioned Hyper-Threading Function. but I did not have it in bios)

Execute Bit Support - I leaved this on, but speed wise off is better, no?

Set Limit CPUID MaxVal to 3 - IMHO off, because who cares about old systems when overclocking, right?

Intel Virtualization Tech - IMHO off for speed?

Intel VT-d - IMHO off for speed?

Active Processor Cores - All - simple there, huh?


Mainboard manual: http://www.mediafire.com/?4vdh50m7ta0995w - https://www.oboom.com/RL8DUVCJ


And then there are the voltage settings:

CPU Voltage(V) - +0.105V

CPU VTT(V) - 1.314V

CPU PLL Voltage(V) - Auto

DRAM Voltage(V) - 1.701V





PCH 1.05(V) - Auto

...any suggestions about how to break the 3.6GHz wall?


And the there are the settings like:

PCI Latency Timer - IMHO the smaller the better, choosen 32 as lowest value

HPET - High Precision Event Timers - no idea what to set, maybe off for speed and less precision?

TCG/TPM SUPPORT - Trusted Platform Module can be enabled/disabled - what is best for speed?


...and don't even get me started about the memory settings. There is 8G consisting of:

2x 2048MB DDR3 1600MHz G.Skill RipJaws 9-9-9-18 1.7V (F3-12800CL9D-4GBRL)

2x 2048MB DDR3 1600MHz Kingston HyperX 9-9-9-18 1.7V (KHX12800D3K2/4G)


So far these seems stable at 860MHz (1720MHz effective) and 1.701Volts, so maybe later some possible finetuning could get handy too :) Current ram settings:


Memory Timing - 2T (Suuuuuuxxx!)

CAS - 9

tRCD - 9

tRP - 9

tRAS - 18

tRFC - 88

tWR - 12

tWTR - 6

tTRRD - 5

tRTP - 6

tFAW - 24

B2B-CAS Delay - 0


tdrRdTRd - 6

tddRdTRd - 7

tsrRdTWr - 11

tdrRdTWr - 11

tddRdTWr - 11

tsrWrTRd - 16

tdrWrTRd - 4

tddWrTRd - 4

tdrWrTWr - 7

tddWrTWr - 7

tsrRdTRd - 4

tsrWrTWr - 4

Round Trip Latency - 59 (channel 1) / 61 (channel 2)


Surely something could be made faster there :)

Edited by trodas
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Hmmm, that is actually great idea, I should have tried that already, lol. Stupid me...


So, I bumped the Vcore to +0.204V (still far cry from +0.278V that the OC genie used) and bumped the VTT to 1.386V (last one before the color get red in the bios) - and x18 multiplier and hell, it booted right away! Whoa!

3780MHz is a bit step from 3578 ... Holly, holly...





...it still freeze in the test, tough :(

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  • 2 weeks later...

Stock cooler - up to 95°C:



Noctua NH-C12P SE14 - up to 61°C:



34°C better temps just by replacing the cooler :D (ambient temperature in both cases 24°C)

And the heatsink use the Noctua NF-P14 FLX fan, witch is pretty inferior to Thermalright TY-140 (141):


16.7 CFM versus 22.6 CFM? Come on, Noctua!




RHRSoul_PC_5.jpg RHRSoul_PC_6.jpg

Edited by trodas
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