Intel Sandy Bridge CPU In-Depth Look at Overclocking, Memory Timings and More

CPU by leeghoofd @ 2011-02-01

First introduced at the CES, Intel’s new Sandy Bridge CPU architecture is here to flood the mainstream market with over 25 CPUs. Don't panic, most are foreseen for the mobile market and only 9 new models will be introduced for the desktop segment. Coinciding with this new release is also a new socket design. 1155 pins will be the new standard for Intel’s mainstream lineup. Yes you guessed it, Sandy bridge is here to replace socket 1156. Slowly but steadily Clarkdale and Lynnfield will become End Of Life and will be phased out. At the Sandy Bridge Tech conference the representatives of Intel said that the current S1366 i7 lineup (Bloomfield and Gulftown) will remain their high end platform. Time to explore Sandy Bridge...

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more tech mumbo jumbo

So still the same name branding, now the below picture will give you already a good idea how the lineup is.

A quick word on the  lineup : so the I7 variants will have 4 cores and 4 hyperthreaded cores allowing up to 8 simultaneous tasks. Core i5 and i3 will support up to max 4 threads. Caching wise i5 and i7 will have access to a max of 8Mb ( this differs on the model ) I3 will only be able to take benefit from max 3Mb cache. All CPUs have got an integrated graphics core. The 2 K  models (2500 and 2600K ) will have the 3000HD IGPU onboard. All the rest is equipped with the 2000HD IGPU.


The above diagram already gives away one of the biggest features on this particular CPU design. What Intel refers to as Last Level Cache is directly accessible by all the onboard CPU components ( cores, IGP, etc...) via a ring architecure. It's not directly comparable with the ATI design on it's graphics cards. but the concept is sort off the same : reduce cache access delays to the maximum.

We were all used to push the Front Side bus on the older Intel platforms and the Bclock out of the 1366 socket to gain some raw Mhz. This however is over and done with, as Intel integrated the clock generator into the CPU now. Sandy Bridge's bclock is controlling every component now and when anything goes out of sync the sytem will be very unstable. Forget about Bclocks of 240 and beyond. The stock Bclock is 100. Expect a max of 105-107ish for the enthousiast overclocking crowd. Theoretical maximum and highest Bclock spotted in the wild is 110. This puts a big damper on overclocking a low end CPU up to the speeds of it's bigger and normally much more expensive brother. If ever you want ot push to higher limits you have to opt for an unlocked multiplier K model. Comparable with the older Extreme models, yet Intel put them only 20 dollars more then the similar speed non K variant.

So we handled the new ring architecture, the shared cache. Last but not least is the dynamic frequency. Alike the previous S1156 platform, but Turbo Boost is enhanced by Intel. Allowing up to 400mhz more if one core is stressed, 300Mhz for dual core usage, 200Mhz for triple core and 100Mhz for quadcore optimised applications. Below you can see again the big difference between a locked and an unlocked K model.

The new Turbo , baptised Intel Turbo boost 2.0 is very impressive. Quickly it adapts to the load demand, thermal factors etc... If you have Intel's Turbo monitor tool open or Tmonitor you will notice constant speed changes between the cores.


Here's a small video of the turbo in action. Stressing with Prime95 v 26.3, first one core, two cores , 4 and finally 8. Look how the cores interact, fluctuate... and look at the CPU-Z CPU speed readout : 37X, 36X, 35X...


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Comment from Teemto @ 2011/02/02
52x102 here with flares at 2176-6/9/6/24
SuperPi and Pifast stable.
Comment from leeghoofd @ 2011/02/02
So use these clocks too then for 3D Pascal
Comment from Teemto @ 2011/02/02
Yes my master.
Comment from thorgal @ 2011/02/03
So which settings did you use for 5Ghz It's those "just a few settings" that interest me

I always want to learn from a master
Comment from Stefan Mileschin @ 2011/02/04
Originally Posted by Teemto View Post
Yes my master.
Is the system stable in 3DMark 2005 CPU test too at those frequencies?
Comment from Teemto @ 2011/02/04
Nope. That's realy the max I could go.
Haven't played around with the other voltages though.
Maybe Albrecht can shed some light if this could improve stability/OC'ability?