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ASUS Support Home Location : Forum > Motherboard > P6T Deluxe  
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  Topic : [Sharing]Overclocking Intel Core i7 processors New Topic
Hiker
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From: SWE
Posted:12/20/2008 7:22:00 PM # 1
This thread is listed in the Elite Posts.

Overclocking Intel Core i7 LGA1366 processors

 

July 11, 2011: Revised due to the release of new processor.

 

 

Preface

 

With the Core i7 900 series processors, all frequencies originate in a Base Clock (BCLK) with a default frequency of 133.33 MHz. From this base frequency, all other frequencies are derived by applying various multipliers.

 

The purpose of this text is mainly to bring an understanding of how to work with the Core i7 900 systems and how different BIOS settings relate to each other, and not so much to present a list of overclocking settings. Hopefully this will help you in finding an overclocking solution for your particular components.

 

Overclocking

 

Easiest to overclock, are the Extreme Editions, Core i7 965 EE, Core i7 975 EE, Core i7 980X and Core i7 990X EE, due to their unlocked CPU multiplier. To overclock the CPU to e.g. 4 GHz, we simply need to raise the CPU multiplier (CPU Ratio Setting) from default 24/ 25/ 25/ 26 (3.20/ 3.33/ 3.33/ 3.46 GHz) to 30 (4.00 GHz), while keeping BCLK at its default frequency, 133 MHz.

 

To achieve the same overclock (4 GHz) on the models Core i7 950 and Core i7 960, the BCLK has to be increased, since their CPU multipliers are upwards locked at 24 for i7 950 and 25 for i7 960. The change of BCLK means that all other clock frequencies are influenced (memory, Uncore and QPI).

 

As an example, overclocking a Core i7 950 to 4 GHz, using the default CPU multiplier (23), would call for an increase of BCLK from default 133 MHz to 174 MHz (4000 / 23 = 174 MHz). That is a substantial overclock that will put stress on different components on the processor chip, which besides the CPU cores also holds the Uncore (the IMC, Integrated Memory Controller, and the L3 cache). There is also the QPI (Quick Path Interconnect), which is a fast bidirectional link between the CPU and the IOH (I/O Hub).

 

The DRAM frequency, the Uncore (UCLK) frequency and, perhaps, the QPI frequency may need to be adjusted according to the new BCLK.

 

 

Core i7 900 series processors – frequency relations

BCLK Frequency

(Base Clock)

Range: 100 – 500

Default: 133.33 MHz

Stability common up to BCLK ~180.

Max out @ BCLK between 180 and 225.

CPU Frequency =

BCLK x CPU Multiplier

4 core, 45nm:

i7 920 – 2.66, i7 930 – 2.80, i7 940 – 2.93,

i7 950 – 3.06, i7 960 – 3.20,

i7 965 EE – 3.20, i7 975 EE – 3.33 GHz

6 core, 32nm:

i7 970 – 3.20, i7 980 – 3.33,

i7 980X EE – 3.33, i7 990X EE – 3.46 GHz

DRAM Frequency =

BCLK x Memory Multiplier

Memory Multipliers*: 6, 8, 10, 12, 14, 16, 18

UCLK Frequency =

BCLK x Uncore Multiplier

≥ 2 x DRAM Frequency

QPI Frequency =

BCLK x QPI Multiplier

QPI Multipliers: 18 (36), 22 (44), 24 (48)

 

 

* Memory Multipliers are invisible in the BIOS of ASUS motherboards. ASUS has chosen to use the resulting DRAM frequencies (BCLK x Memory Multipliers) instead.


 

 

Multipliers / Frequencies @ BCLK = 133 MHz

Note that all frequency options below change with the BCLK

Processor

Model

CPU Ratio Setting

(Multiplier)

Memory

Multiplier

UCLK (Uncore)

Multiplier

QPI

Multiplier

Core i7 920

2.67 GHz

12 – 21

Default 20

 

6, 8, 10, 12,

14, 16, 18

(DDR3-800)

(DDR3-1066)

(DDR3-1333)

(DDR3-1600)

(DDR3-1866)

(DDR3-2133)

(DDR3-2400)

 

≥ 2 x Memory Multiplier

12, 13, 14, 15, ….., 26

(1600MHz)

(1733MHz)

(1866MHz)

(2000MHz)

(2133MHz)

(2266MHz)

(2400MHz)

(2533MHz)

(2666MHz)

(2800MHz)

(2933MHz)

(3066MHz)

(3200MHz)

(3333MHz)

(3466MHz)

 

18, 22, 24

2400MHz

2933MHz

3200MHz

or

(36, 44, 48)

(4800 MT/s)

(5866 MT/s)

(6400 MT/s)

 

Core i7 930

2.80GHz

12 – 22

Default 21

Core i7 940

2.93 GHz

12 – 23

Default 22

Core i7 950 **

3.06 GHz

12 – 24

Default 23

Core i7 960 **

3.20 GHz

12 – 25

Default 24

Core i7 965

Extreme

3.20 GHz

12 – 63

Default 24

 

Core i7 975

Extreme

3.33 GHz

12 – 63

Default 25

 

Core i7 970 **

6 core, 32nm

3.20 GHz

12 – 25

Default 24

Core i7 980 **

6 core, 32nm

3.33 GHz

12 – 26

Default 25

Core i7 980X

6 core, 32nm

eXtreme

3.33 GHz

12 – 63

Default 25

Core i7 990X **

6 core, 32nm

eXtreme

3.46 GHz

12 – 63

Default 26

 

** Presently manufactured model

 

 

ASUS has chosen to use the resulting frequencies instead of the multipliers in BIOS.

The available options for DRAM Frequency depend on the BCLK.

The available options for UCLK depend on the DRAM Frequency.

The available options for QPI depend on the BCLK.

 

Intel® TurboMode Tech (enabled by default)

 

When TurboMode Tech is enabled, the CPU multiplier may automatically increase with 1. With only 1 core active, the CPU Multiplier may increase with 2.

The CPU Ratio Setting has to be set to [Auto] to allow this function.

 

 

Strategy for overclocking

 

To simplify a stable overclocking, different strategies can be used. I’ll here focus on the Core i7 models Core i7 950/960. The Extreme Editions (Core i7 965, Core i7 975, Core i7 980X and Core i7 990X) are easier to overclock, due to their unlocked CPU multiplier, which eliminates the need to raise the Base Clock (BCLK).

You may want to raise BCLK to match the rated memory speed with the desired CPU speed though.


 

Core i7 950:

How to calculate the overlock - example.

A good starting point could be to calculate which BCLK you would need, to achieve your desired CPU speed. Let’s say that you would like a CPU speed of 3.6 GHz. The needed BCLK then is: 3600 / 24 = 150MHz, using the highest option for the CPU Ratio Setting, which is 24, manually set, for Core i7 950. CPU speed will be: BCLK x CPU Ratio Setting = 150 x 24 = 3600MHz (3.6GHz)

 

Let’s say that you want to use a DDR3-1600MHz memory. Determine the memory multiplier as DRAM Frequency / BCLK (1600 / 150 = 10.67) Use the nearest memory multiplier, which is 10. The nearest selectable option for DRAM Frequency will then be BCLK x memory multiplier (150 x 10 = 1500). Select DRAM Frequency [DDR3-1500] (which means a rather insignificant underclock of the memory).

 

The UCLK (Uncore) multiplier should be greater than, or equal to, 2 x the memory multiplier: 2 x 10 = 20.

Uncore Frequency is BCLK x UCLK multiplier (150 x 20 = 3000). Select UCLK Frequency [3000MHz].

This setting can also be left at [Auto].

 

The QPI (Quick Path Interconnect) is a high speed, bi-directional, link between the CPU and the X58 IOH (I/O Hub). There is hardly anything to gain from increasing the multiplier from the default value (18) so we leave it at that. This means a QPI Frequency of 150 x 18 = 2700MHz, or 150 x 36 = 5400MT/s (Mega Transfers per second).

This setting is preferably set manually to the lowest option when overclocking by raising the BCLK.

 

Next step is to lower the CPU Ratio Setting to 14 and run Memtest86+ v4.20 (or later) to verify the stability for memory, Uncore and QPI, without the risk of limitations due to the CPU speed. If errors occur, try to increase the QPI/DRAM Core Voltage.

 

If Memtest86+ runs error free, set the CPU Ratio Setting to 24 or [Auto]. The setting [Auto] means default 23 for i7 950, but with TurboMode Tech enabled, the CPU Ratio Setting will normally be 24.

 

Finally, running Prime95 for a total of 8 virtual cores, the PC has to be stable for at least overnight.

 

 

Manual configurations

 

Ai Overclock Tuner

Manual

Allows you to individually set overclocking parameters. (Recommended when overclocking).

Auto

Loads the standard settings for the system.

D.O.C.P.

Overclocks DRAM Frequency by adjusting the BCLK frequency.

X.M.P.

If you install memory modules supporting eXtreme Memory Profile (XMP) technology, choose this item to set the profile supported by your memory modules for optimizing the system performance.

 

CPU Voltage [1.20V – 1.375V] (total range: 0.85V-1.70V (2.10V)).

Initially I recommend leaving this setting at [Auto]. That means that the CPU Voltage is set according to the VID (Voltage Identification Code). VID is automatically adjusted, in steps, according to the CPU frequency. Since the setting [Auto] in many cases gives an unnecessary high CPU Voltage, resulting in an unnecessary high CPU temperature, I recommend tweaking this voltage manually when you are happy with your overclock (see Voltage optimization below).

 

CPU PLL Voltage [Auto] or [1.80V – 2.10V] (total range: 1.80V-2.50V).

 

DRAM Bus Voltage [max 1.65V] (1.64V-1.66V) (total range: 1.50V-1.90V (2.46V)) Intel states, that a DRAM Bus Voltage beyond 1.65V may permanently damage the processor.

If a lower voltage than 1.65V is specified for your memory, then use the specified voltage.

For DDR3-800MHz - DDR3-1333MHz memory, the voltage normally is 1.5V (JEDEC standard voltage for DDR3 memory).


 

QPI/DRAM Core Voltage [1.20V – 1.40V] (total range: 1.20V-1.70V (1.90V)).

QPI/DRAM Core Voltage must be within 0.5V of the DRAM Bus Voltage. This could only be an issue when the DRAM Bus Voltage is set very high (1.71V-2.46V).

This voltage setting is very important. DDR3-1600MHz memory may need this voltage to be 1.35V and DDR3-2000MHz may need as much as 1.65V. I recommend setting this voltage manually, and when you are happy with your overclock, tweak the voltage (see Voltage optimization below).

 

The other voltages may be left at default (Auto).

 

BCLK Frequency [XXX] (default 133 MHz, range: 100-500 MHz)

DRAM Frequency [DDR3-XXXX] (range: DDR3-800MHz – DDR3-2000MHz)

According to Intel’s specification, only DDR3-800MHz and DDR3-1066MHz are supported. Using DDR3-1333MHz memory, and higher frequencies, would mean overclocking (of the IMC).

(Tests have shown that there is a very small performance gain in using faster memory than DDR3-1333MHz).

PCIE Frequency [100] (locks the PCIE frequency)

Tweaking in the range of 100-110 may be necessary.

 

Voltage optimization

At least CPU Voltage and QPI/DRAM Core Voltage should be set manually.

When you are satisfied with your overclock, I recommend optimizing CPU Voltage and QPI/DRAM Core Voltage, which means finding the lowest possible voltage where 100% Prime95 stability is maintained for at least overnight.

 

Start with optimizing the CPU Voltage by lowering the CPU Voltage by 1-2 notch(es) at a time, until Prime95 stops the execution within 10 minutes – then increase the voltage by 1 notch at a time and test again. In the end, Prime95 should be able to run for at least overnight.

 

Use Prime95, the same way as described for the CPU Voltage, to find the lowest possible QPI/DRAM Core Voltage that allows the PC to run error free under stress for at least overnight.

 

Finally, run Memtest86+ (version 4.20, or later) to verify that Memtest86+ runs totally error free for at least overnight. If any error, try with increasing QPI/DRAM Core Voltage by 1 notch at a time until Memtest86+ runs error free.


 

 

Overclockings for Core i7 950 / Core i7 960

Base Clock

(BCLK)

MHz

Memory

Multiplier

DRAM Freq. MHz

Uncore

Multiplier

UCLK Freq.  MHz

QPI

Multiplier

QPI Freq. MT/s

CPU i7 950

Multiplier

Freq. GHz

CPU i7 960

Multiplier

Freq. GHz

133.33

6 ó DDR3-800

12 ó 1600

18 (36) ó 4800

24 ó 3.20

25 ó 3.33

133.33

  8 ó DDR3-1066

16 ó 2133

18 (36) ó 4800

24 ó 3.20

25 ó 3.33

133.33

10 ó DDR3-1333

20 ó 2666

18 (36) ó 4800

24 ó 3.20

25 ó 3.33

133.33

12 ó DDR3-1600

24 ó 3200

18 (36) ó 4800

24 ó 3.20

25 ó 3.33

133.33

14 ó DDR3-1866

28 ó 3733

18 (36) ó 4800

24 ó 3.20

25 ó 3.33

133.33

16 ó DDR3-2133

32 ó 4266

18 (36) ó 4800

24 ó 3.20

25 ó 3.33

133.33

18 ó DDR3-2400

36 ó 4800

18 (36) ó 4800

24 ó 3.20

25 ó 3.33

143

14 ó DDR3-2002

28 ó 4004

18 (36) ó 5148

24 ó 3.43

25 ó 3.57

150

10 ó DDR3-1500

20 ó 3000

18 (36) ó 5400

24 ó 3.60

25 ó 3.75

155.67

12 ó DDR3-1868

24 ó 3736

18 (36) ó 5604

24 ó 3.73

25 ó 3.89

160

10 ó DDR3-1600

20 ó 3200

18 (36) ó 5760

24 ó 3.84

25 ó 4.00

166.67

  8 ó DDR3-1333

16 ó 2666

18 (36) ó 6000

24 ó 4.00

24 ó 4.00

166.67

10 ó DDR3-1666

20 ó 3333

18 (36) ó 6000

24 ó 4.00

24 ó 4.00

166.67

12 ó DDR3-2000

24 ó 4000

18 (36) ó 6000

24 ó 4.00

24 ó 4.00

177.67

  6 ó DDR3-1066

12 ó 2132

18 (36) ó 6396

22 ó 3.91

22 ó 3.91

180

  8 ó DDR3-1440

16 ó 2880

18 (36) ó 6480

22 ó 3.96

22 ó 3.96

185

  8 ó DDR3-1480

16 ó 2960

18 (36) ó 6660

22 ó 4.07

22 ó 4.07

190

  8 ó DDR3-1520

16 ó 3040

18 (36) ó 6840

21 ó 3.99

21 ó 3.99

191

  8 ó DDR3-1528

16 ó 3056

18 (36) ó 6876

21 ó 4.01

21 ó 4.01

195

  8 ó DDR3-1560

16 ó 3120

18 (36) ó 7020

21 ó 4.09

21 ó 4.09

200

  6 ó DDR3-1200

12 ó 2400

18 (36) ó 7200

20 ó 4.00

20 ó 4.00

200

  8 ó DDR3-1600

16 ó 3200

18 (36) ó 7200

20 ó 4.00

20 ó 4.00

180

10 ó DDR3-1800

20 ó 3600

18 (36) ó 6480

22 ó 3.96

22 ó 3.96

186.67

10 ó DDD3-1867

20 ó 3734

18 (36)