Recently we completed a clock for clock CPU article comparing various quad-core processors from AMD and Intel. The new Core i5 750 was among the pack and we were surprised by what this processor had to offer in terms of performance, especially given it costs just $200 US. When comparing the Core i5 750 against the bigger more expensive LGA1366 (Core i7 9xx) processors the results were surprising.

Impressively there was almost no difference between the performance of the Core i5 750 and the Core i7 860/920 processors when working at the same frequency. In the end the results further cement our beliefs that the Core i5 750 is the best value quad-core processor available at the moment, with no exception.

Furthermore, they also provide us with evidence that overclockers need not bother with the Core i7 8xx series, as there is nothing to be gained when pushing them to 3.60GHz and beyond. The Core i5 750 is already great value before any kind of overclocking takes place. However push it to beyond 3.0GHz and you start to receive Core i7 9xx series performance, and if you go even further the Core i5 750 starts to come into a league of its own.

The best thing about Core i5 750 overclocking is that it’s very easy, especially if you choose the right hardware. At the moment I am working on a large P55 motherboard roundup that covers boards from several different manufacturers. One of the ways that we are comparing these motherboards is based on their overclocking abilities, and this is where the ASUS P7P55D series has really stood out.

To date I have overclocked a number of Core i5 750 processors on a range of ASUS P55 motherboards, which includes the ASUS P7P55D, ASUS P7P55D PRO, ASUS P7P55D EVO and ASUS P7P55D Deluxe. These boards range in price from $150 US through to $220 US, so there is something for everyone. What we have noticed is despite which model you choose, they are all capable of some pretty amazing overclocks with the Core i5 750 processor.

By default the BCLK Frequency will be set to 133MHz, while the Core i5 750 clock multiplier with turbo mode disabled is 20x. Using the standard box cooler we had no problem with a base clock frequency of 166MHz, though we should point out that this increased stress temperatures from 71 degrees to a toasty 95 degrees.

Before we reveal anything else about the overclock, let’s just run through the overclocking options within the BIOS of the ASUS P7P55D motherboards. Once the Ai Overclock Tuner option has been set to manual, the first option the user is presented with is the CPU Ration Setting. This option can be left on [Auto], which we recommend, to fix at 20x or lower. We are leaving this option on auto as it will allow us to use Intel’s Turbo mode.

The next option is called Intel SpeedStep and this is a dynamic frequency scaling technology that is built into the Core i5 750, that allows the clock speed of the processor to be dynamically changed by software. This allows the processor to meet the instantaneous performance needs of the operation being performed, while minimizing power draw and heat dissipation.

Then there is the Intel TurboMode feature, which has been implemented by Intel in their Core i5 and Core i7 CPUs, and is actually known as “Turbo Boost”. This feature also sees the CPUs performance dynamically increased on demand and is activated when the operating system requests the highest performance state of the processor. There are a few parameters that determine the upper limit of Intel Turbo Boost technology, such as number of active cores, estimated current consumption, estimated power consumption, and processor temperature.

The next option is called “Xtreme Phase Full Power Mode” and is the setting that disables the EPU functions and provides full power to all phases. This is a recommended requirement when overclocking and therefore should be enabled.

The other options that will be of interest include the BCLK Frequency, PCIE Frequency, DRAM Frequency, and QPI Frequency. Depending on the BCLK frequency you choose, this will determine what DRAM frequency options you have available. For example, if you choose a BCLK frequency of 200MHz the DDR3 frequencies that will be available are 1200MHz, 1600MHz, and 2000MHz.

Most modern DDR3 memory kits will be capable of 1600MHz depending on the timings, so this should be a safe option. The ASUS P7P55D motherboards provide memory multipliers of 3x, 4x, and 5x. The PCIE Frequency can be adjusted if need be, though we were able to leave it at 100MHz, while we left the QPI Frequency on auto.

Other than the BCLK Frequency and DRAM Frequency, we actually changed nothing else in the BIOS and these two options alone allowed us to overclock our Core i5 750 processor to an incredible 4.20GHz. The ASUS P7P55D motherboards allow the user to set the CPU Voltage to auto using an offset mode. This means the motherboard will automatically adjust the CPUs voltage depending on the frequency. For example, at idle the CPU required just 1.128v, while under load this figure was increased to 1.512v.

Note: The below settings were entered using the ASUS P7P55D Deluxe motherboard with the latest “606” BIOS, though we have found that previous BIOS revisions were much the same in terms of layout and overclocking abilities.

AI Overclock Tuner
AI Overclock Tuner Mode : Manual
CPU Ratio Setting : [Auto]
Intel(R) SpeedStep(TM) Tech : [Enabled]
Intel(R) TurboMode Tech : [Enabled]
Xtreme Phase Full Power Mode : [Enabled]
BCLK Frequency : 200MHz
PCIE Frequency : 100MHz
DRAM Frequency : 1600MHz
QPI Frequency : [Auto]
Channel Interleave : 6
Rank Interleave : 4

DRAM Timing Control Sub Menu
1st Information
DRAM CAS# Latency (tCL ) : [Auto] 9
DRAM RAS# to CAS# Delay (tRCD ) : [Auto] 9
DRAM RAS# PRE Tine (tRP) : [Auto] 9
DRAM RAS# ACT Tine (tRAS) : [Auto] 24
DRAM RAS# to RAS# Delay (tRRD) : [Auto] 6
DRAM REF Cycle Time (tRFC) : [Auto] 89
DRAM WRITE Recovery Tine (tWR) : [Auto] 13
DRAM READ to PRE Time (tRTP) : [Auto] 8
DRAM FOUR ACT WIN Time (tFAW) : [Auto] 31
2nd Information
Timing Mode (CMDR) : [Auto] 1N
DRAM Round Trip Latency on CHA : [Auto] 59
DRAM Round Trip Latency on CHB : [Auto] 61
3rd Information
DRAM WRITE To READ Delay(DD) : [Auto] 6
DRAM WRITE To READ Delay(DR) : [Auto] 6
DRAM WRITE To READ Delay(SR) : [Auto] 18
DRAM READ To WRITE Delay(DD) : [Auto] 10
DRAM READ To WRITE Delay(DR) : [Auto] 10
DRAM READ To WRITE Delay(SR) : [Auto] 10
DRAM READ To READ Delay(DD) : [Auto] 7
DRAM READ To READ Delay(DR) : [Auto] 6
DRAM READ To READ Delay(SR) : [Auto] 4
DRAM WRITE To WRITE Delay(DD) : [Auto] 7
DRAM WRITE To WRITE Delay(DR) : [Auto] 7
DRAM WRITE To WRITE Delay(SR) : [Auto] 4

Dram Driving & SlewRate Control Sub Menu
CMD Driving Up Ctrl : [Auto]
CMD Driving Down Ctrl : [Auto]
DQ Driving Up Ctrl : [Auto]
DQ Driving Down Ctrl : [Auto]
CLK SlewRate Ctrl A : [Auto]
CLK SlewRate Ctrl B : [Auto]
CMD SlewRate Ctrl : [Auto]
CTRL SlewRate Ctrl : [Auto]
DQ SlewRate Ctrl : [Auto]

Dram Skew Control Sub Menu
Address Floating Control : [Enabled]
DRAM CLK Delay Patch Location : [Before CLK Trainin]
DRAM ODTO Delay on Channel A : [Auto]
DRAM CLKO Delay on Channel A : [Auto]
DRAM CMDA Delay on Channel A : [Auto]
DRAM WDQS0 Delay on Channel A : [Auto]
DRAM TXDQO Delay on Channel A : [Auto]
DRAM RXDQSO Delay on Channel A : [Auto]
DRAM ODTO Delay on Channel B : [Auto]
DRAM CLKO Delay on Channel B : [Auto]
DRAM CMDA Delay on Channel B : [Auto]
DRAM WDQS0 Delay on Channel B : [Auto]
DRAM TXDQO Delay on Channel B : [Auto]
DRAM RXDQSO Delay on Channel B : [Auto]

AI Overclock Tuner Continued
CPU Voltage Mode : [Offset]
Offset Voltage : [Auto]
IMC Voltage : [Auto]
DRAM Voltage : [Auto]
CPU PLL Voltage : [Auto]
PCH Voltage : [Auto]
DRAM DATA REF Voltage on A : [Auto]
DRAM CTRL REF Voltaqe on A : [Auto]
DRAM DATA REF Voltaqe on B : [Auto]
DRAM GIRL REF Voltaqe on B : [Auto]
Load Line Calibration : [Disabled]
CPU Spread Spectrum : [Disabled]
PCIE Spread Spectrum : [Disabled]

CPU Settings
CPU Ratio Setting : [Auto]
C1E Support : [Enabled]
Hardware Prefetcher : [Enabled]
Adjacent Cache Line Prefetch : [Enabled]
Max CPUID Value Limit : [Disabled]
Intel (R) Virtualization Tech : [Enabled]
CPU TM Function : [Enabled]
Execute-Disable Bit Capability : [Enabled]
Active Processor Cores : [All]
A2OM : [Disabled]
Intel(R) SpeedStep(TI1) Tech : [Enabled]
InteI (R) TurboMode Tech : [Enabled]
Intel C-Start Tech + : [Disabled]

Intel LGA1366 System Specs - Intel Core i7 920 (LGA1366) - x3 Kingston HyperX 2GB DDR3-1333 (CAS 8-8-8-24) - ASUS P6T Deluxe (Intel X58) - OCZ GameXStream (700 watt) - Seagate 500GB 7200-RPM (Serial ATA300) - HIS Radeon HD 5850 (1GB) Software - Microsoft Windows 7 Ultimate (64-bit) - ATI Catalyst 9.10

Intel LGA1156 System Specs - Intel Core i5 750 (LGA1156) - x2 Kingston HyperX 2GB DDR3-1333 (CAS 8-8-8-24) - ASUS P7P55D Deluxe (Intel P55) - OCZ GameXStream (700 watt) - Seagate 500GB 7200-RPM (Serial ATA300) - HIS Radeon HD 5850 (1GB) Software - Microsoft Windows 7 Ultimate (64-bit) - ATI Catalyst 9.10

Intel Core 2 Quad System Specs - Intel Core 2 Quad Q9650 (LGA775) - x2 Kingston HyperX 2GB DDR3-1333 (CAS 8-8-8-24) - ASUS Rampage Extreme (Intel X48) - OCZ GameXStream (700 watt) - Seagate 500GB 7200-RPM (Serial ATA300) - HIS Radeon HD 5850 (1GB) Software - Microsoft Windows 7 Ultimate (64-bit) - ATI Catalyst 9.10

Our maximum overclock of 4.2GHz saw a 37% increase in read performance and a massive 53% rise in write performance when testing with MaxxPI². This overclock provided our Core i5 750 processor with considerably more memory bandwidth than the Core i7 920 processor.

The MaxxPI² Prime test saw the throughput of our overclocked Core i5 750 processor increase substantially. The single thread performance was boosted by 50% while the multi-threaded performance more than doubled.

Finally we ran the overclocked Core i5 750 processor through WinRAR. The multi-threading performance increased by 34%, while the single thread performance was boosted by 31%.

The above graph shows how the bump in frequency increases the amount of power required by the CPU. Under load the standard Core i5 750 configuration uses just 170 watts of power for the entire system. When overclocked to 3.48GHz the required power when under load increased by 36% to 231 watts. Then at 4.20GHz the system power consumption level hit 285 watts, which is a 68% increase over the non-overclocked configuration.

Next we have some results covering operating temperatures. Please note that the 4.20GHz overclock was achieved using the Noctua NH-U12P SE2 cooler, while we also used the standard Intel box cooler at 3.48GHz. As you can see at 3.48GHz the standard box cooler allowed the Core i5 750 processor to reach a rather toasty 95 degrees! When swapping out the standard box cooler for the Noctua NH-U12P SE2 we were not only able to reach 4.20GHz, but we did so with a stress temperature of just 85 degrees.

That said there are quite a number of other great quality P55 motherboard series out there and we believe you will have a lot of overclocking success with most of them. Something to remember is that although we never touched the voltage for the Core i5 750 in the BIOS when at 4.20GHz the P7P55D motherboard did jack it up to 1.512v to maintain stability and therefore this is the voltage target you should be aiming for.

Of course not everyone is going to be able to purchase a Core i5 750 processor along with an ASUS P7P55D motherboard and hit a 4.20GHz right off the bat. That said we believe your chances are good as we have tested four processors now and all hit the magical 4.20GHz first time with 100% stability. Still it is best to start at a lower base clock and work your way up.

Given that the default base clock is 133MHz we suggest you try 166MHz and stress test at this frequency for a few hours and monitor temperatures. Then if all goes well bump the base clock up a little more until you reach 200MHz. Again all we were required to change was the base clock as the P7P55D motherboards will automatically adjust the voltage for you.

On a side note we use the latest version of Prime95 to stress test our processors but there are other programs out there that do that same job. Also worth mentioning is that we use EVEREST Ultimate Edition to monitor system temperatures and again there are quite a number of programs that can do this for you.

When testing an overclock for stability it is best to leave a program such as Prime95 running for a few hours to help ensure that you will not encounter any unexpected crashes while gaming or dare I say it hard at work!” Also when stress testing make sure you do use a program such as Prime95 and we strongly recommend you try and keep the maximum temperature below 90 degrees.

As always cooling is a vital aspect of overclocking and we found that the Intel box cooler was really inadequate at even 3.48GHz as stress temperatures hit 95 degrees. Still with a high-performance air cooler such as the Noctua NH-U12P SE2 we were able to keep temperatures at 85 degrees when operating at 4.20GHz.

However keep in mind that the Noctua NH-U12P SE2 does cost $65 US though that price does include a pair of 120mm fans. Still this means that a Core i5 750, ASUS P7P55D and Noctua NH-U12P SE2 combo will set you back just over $400 US. That’s not bad for a hardware configuration that can blow away any desktop with a few quick tweaks.

Please feel free to post any comments or questions you may have regarding this article "HERE". Furthermore, if you have any problems with your overclock we are more than happy to try and help you solve the problem. That said, we are also very keen to hear from users that have successfully overclocked their Core i5 750 processor, either using our article or coming up with their own solution.

Reviewed By Steven Walton