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Intel Sandy Bridge Overclocking Guide E-mail
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Written by Servando Silva   
Tuesday, 19 April 2011
Table of Contents: Page Index
Intel Sandy Bridge Overclocking Guide
Why Should I Overclock?
Overclocking Applications and Utilities
Processor Stability Testing
Understanding OC Variables
UEFI and Testing Methodology
Overclocking Frequency vs. Voltage
Overclock vs. Power Consumption
Overclock vs. Temperatures
Final Thoughts

Understanding OC Variables

There are some basic variables you should really check while overclocking. Based on these variables, you'll be able to achieve 90% of your overclocking process and actually reach a stable and very decent frequency without messing a lot with weird numbers and values. Please refer to your motherboard's manufacturer to locate the BIOS reset switch/jumper before starting to overclock. This jumper will be very helpful if you reach a completely unstable state where the PC won't BOOT anymore. Don't panic, just turn off your computer and press/short the appropriate pins to reset your settings. Some other manufacturers implement an auto-recovery feature which (in case the PC doesn't BOOT) will recover your settings after trying to POST a couple of times without achieving it.

Now you should really have a look at your BIOS/UEFI and identify the section where all the next parameters are found. If there's a possibility to save different profiles (many motherboards feature multiple OC profiles) save a copy of your default's profile.

CPU Frequency: This frequency is calculated by multiplying CPU multiplier x BCLK. Until Intel LGA775 sockets, this frequency was calculated by multiplying CPU multiplier x Front Side Bus. Intel Core iX processors changed this FSB for a Base Clock (BCLK) which is the basis to all the parameters I'll explain below. CPU frequency is 100% related to overall speed, and thus, it's the most important factor when overclocking your setup.

BCLK: This value is the key to obtain all other values, since all of them are BCLK multiples. I won't really go deep into this value as its overclocking capabilities are way below they used to be. 100MHz is the default value but you can usually get 3-5 extra MHz or even a little bit more if you happen to have a good CPU+Motherboard.

CPU Multiplier: As its name says, this multiplier gives you the final CPU frequency value. For Sandy Bridge processors, this multiplier is higher than LGA775 CPUs. This means BCLK doesn't need to be as high as FSB to reach outstanding frequencies. With Sandy Bridge unlocked processors, this is the key to get a superb overclock. While the theoretical limit is 57x, many processors stop at 53-54x. I wouldn't be mad at that as that means I could get more than 5GHz, which is a frequency normally impossible to stabilize.

RAM Memory Multiplier: This multiplier is directly affected by BCLK and results into a final memory speed. Since we're not overclocking the BCLK that much with Sandy Bridge platforms, memory won't affect that much.

CPU EIST & Speedstep: Properly used, this technology allows CPU frequency transition between low and high states. By changing CPU voltage and lowering CPU frequency, the CPU is able to consume less power at idle mode, while increasing values whenever any process is detected. Those features can be very useful if you want to overclock your PC while keeping low temperatures and power consumption at idle mode. Unluckily, many manufacturers disable these features when you start overclocking, letting CPU voltage/frequency at their max state all the time.

Turbo Boost: This feature is inherent to Core i5/Core i7 processors only. By monitoring which cores are processing information, Turbo Boost allows them to increase CPU multipliers individually for each core, increasing final speed by 1 to 4 multiples while the rest of the cores (unused) remain at stock speeds. It's best to disable this feature when overclocking since that will make it easier to find your CPU's sweet spot. However, you can set a lower CPU frequency and let Turbo Boost reach your maximum tested overclock if you prefer.

Load-line Calibration: Also named as vDroop compensation or LLC, this feature increases CPU voltage to balance it between different states. At full load, CPU vCore droops to keep levels at Intel's specifications. While enabling LLC will give you the ability to run more MHz with "lower" voltage, this feature falls against Intel specifications, and it's not recommended, especially when you're aiming to increase vCore a lot. With Sandy Bridge introduction, LLC has become a very important value to enable in order to achieve high overclocks. Many people found that LLC enabled their CPU to reach way higher CPU multipliers, so, most of the motherboards in the market now support LLC.

PCI-E Frequency: Normally set at 100MHz, this value could help a little while overclocking your system and GPU. Try keeping it below 115MHz as it could produce S-ATA drives corruption. I normally set this value to 101MHz as a rule.

Voltage Values

If you're willing to sacrifice temperatures and power consumption to reach higher speeds, you must mess with voltages. You need to be very careful with these values since you'll be adding extra heat and electron-migration to the components. Personally, I find it better to reach maximum CPU frequency with stock voltage and let it stay there. That's because at that point, you'll be gaining speed while keeping your CPU cool enough. This will also increase power consumption by no more than 5-10 watts. Adding voltage can reach a point where CPU speed won't be comparable to the heat and power consumed, ending with lower efficiency results.

CPU vCore: This value is related to CPU frequency. If you want to get extra MHz, you'll need to add vCore to your CPU. CPU vCore is also 100% related to CPU temperature and final power consumption. With Sandy Bridge, I'd recommend keeping it below 1.4-1.45 volts. Normally, a 4 core CPU running at those voltages will reach 70-80 degrees even with a high-performance cooler.

VCCSA: This is the System Agent voltage which in this case means Integrated Memory Controller. Since Sandy Bridge IMC has proven to be very robust, it's not really needed unless you want to reach super high memory frequencies or while using all the 4 memory slots. Usually 1.15v should be OK for anything and many overclockers recommend not going above 1.2 volts.

VDIMM/DRAM Voltage: Related to RAM memory, you'll need to increase VDIMM voltage to achieve higher RAM frequencies. Contrary to CPU vCore, different RAM kits need different voltages and they might get to a point where adding voltage won't help anymore depending on the integrated circuits (ICs) built on your memory kit.

As you can see, overclocking has been severely reduced to something easier to practice. In fact, every time we see a new platform coming it normally means we need to learn what the key-values and limits are again. With Sandy Bridge, however, overclocking has become much easier than before, to the point where Intel launched a video where even your grandmother overclocks the PC. If you don't want to mess up with memory timings and frequencies then vCore and CPU multiplier are the values you'll need to check and modify to achieve a decent overclock.



 

Comments 

 
# RE: Intel Sandy Bridge Overclocking GuideJackNaylorPE 2011-04-21 12:37
Would have liked to see a comparison of setting the Turbo / Voltage to a fixed number versus using the Max turbo frequency / voltage offset method.
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# RE: RE: Intel Sandy Bridge Overclocking GuideServando Silva 2011-04-21 13:53
Hi Jack. Please check our forum as I've just explained why I didn't test that way. It would need another article just for that, or at least, a new set of tests.
Take care.
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# RE: Intel Sandy Bridge Overclocking GuideRobert17 2011-04-21 13:24
Nicely done. But you did make it seem like the "good old days" of mounting a PVC tank with a fish-tank pump feeding from an ice chest full of frigid water may be a thing of the past.

Not to get too far away from your core article regarding Sandy Bridge, but do you have any insight as to whether or not AMD will maintain OC potential in their new lineup?
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# RE: RE: Intel Sandy Bridge Overclocking GuideServando Silva 2011-04-21 13:57
Yeah. I've been overclocking for the last 10 years and I know many others who have been doing it for 15 years or so.
You know that phrase: "Like the old days". I'm not saying I don't like this new way of overclocking. Actually, I like not to pass several hours to find such a nasty or complex configuration for my PC, and doing it the the old way. New OC tools and features help a lot when what you just need is to bump your PC speed and get back to work, but sometimes it was funny to test and read a lot for that.
Also, sub-zero overclocking is quite fun, but with Sandy Bridge they somehow killed it.

Regarding the new AMD processors, I still have no information about them, so I'm anxious to test one.
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# RE: RE: RE: Intel Sandy Bridge Overclocking GuideDavid Ramsey 2011-04-21 14:30
The new way of overclocking-- raising the maximum multiplier use by Turbo Boost-- has one huge advantage over the old ways of increasing BCLK or the base multiplier: to wit, the processor can still downclock to low speeds when you don't need the performance. My 4.1gHz 980x always runs at 4.1gHz. A 4+gHz Sandy Bridge can idle at the same speed it does non-overclocked, saving a lot of power (and generating less heat).
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# RE: RE: RE: RE: Intel Sandy Bridge Overclocking GuideRobert17 2011-04-21 15:51
I'm not complaining. Maybe just pining a bit. I set up a simple OC on my MB, seldom vary it due to the stability, change to game, pretty much ignoring the power consumption. My bad. What limited understanding I have of UEFI seems to indicate that rebooting to change configs may become simpler.

And certainly the advantages of having a MB/CPU combo that is "self-monitoring" power, thrust, pitch and yaw outweigh the "good old days". And yes, I mostly like automatic transmissions over three-on-the-tree these days as well.
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# RE: RE: RE: RE: Intel Sandy Bridge Overclocking GuideServando Silva 2011-04-22 11:45
Completely true! As I've said. I'm not really complaining. I like the new way as it benefits final users. It's just they took away that "chilli spice" when overclocking. Also, they limited it to Unlocked processors and certain platforms.
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# RE: RE: RE: Intel Sandy Bridge Overclocking GuideOlle P 2011-04-22 10:30
"... sub-zero overclocking is quite fun, but with Sandy Bridge they somehow killed it."

You can say that again! I read somewhere that Sandy Bridge reach its peak performance at about 20C. If you cool it more than that it won't reach quite as high speeds.
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# RE: RE: RE: RE: Intel Sandy Bridge Overclocking GuideServando Silva 2011-04-22 11:48
Do you want me to say it louder? Yeah!
I've heard some processors do worst when going below 10-20C degrees. Again, it's good because now many users will be able to play and overclock without going extreme, but it won't be as interesting for extreme users.
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# RE: Intel Sandy Bridge Overclocking GuideJackNaylorPE 2011-04-24 15:35
One other thing I'd love to see addressed ... POITA ain't I :) ..... the 2600k I assume is running hotter cause of the HT..... Prior to reading the article, I cam to the same conclusion that 4.4 Ghz was the sweet spot for the 2600k for 24/7/365. Since this was a B'day build for Son No. 3, w/ Spring break and all I haven't been able to get near the thing in a week.....I used the Asus BIOS Profile feature to store OC Profiles from 4.0 to 4.8 GHz w/ these temps on the SIlver Arrow cooler:

Max Core Temps under (Idle - P95 load)

GHz..... 3.8 ... 4.00 ...... 4.2 ........ 4.4 ........ 4.6 ....... 4.80
Core 1 (51) (31 - 52) (29 - 54) (29 - 56) (31 - 62) (29 - 69)
Core 2 (53) (30 - 54) (30 - 56) (30 - 60) (31 - 66) (28 - 75)
Core 3 (53) (23 - 55) (22 - 57) (22 - 60) (31 - 68) (28 - 79)
Core 4 (51) (29 - 52) (28 - 55) (29 - 57) )31 - 65) (28 - 72)

Hope that formats well

What I am thinking now is making a "gaming profile" w/ HT turned off since I can prolly drop 7 - 10C at 4.8 Ghz ..... will give it a # when kid gets back in school but wondering if anyone's tried yet on SB.
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