With the introduction of the new Intel Core i7 processor architecture, the company affectionately known as "Chipzilla" from Santa Clara has once again topped itself on the performance charts. Core i7 chips deliver significantly better performance per clock cycle, while at the same time being more power-efficient versus its predecessors. There's no doubt that it's a great chip, an insanely complex piece of circuitry which can churn through whatever you throw at it with relative ease. It is the chip you want in your system, assuming price is no barrier. However, in this economic environment, price is a major factor for most people out there, and lots of people out there are looking for a bargain, or at least, something to make the price tag more tolerable.

As with any new processor architecture introduction, early adopters bear the brunt of the cost on these new chips. If you were to set up a high-end Core i7 system today (Core i7 965, X58 motherboard, 6 GB DDR3-1600 memory), you're looking at a price tag of around $1,500 - $2,000, without any graphics cards or storage or extras. However, it is possible to get similar performance levels of a top-of-the-line Core i7 system without paying nearly as much, and that's through the time-honored tradition of overclocking.

Intel planted a gift in the Core i7 launch in the form of the Core i7 920. This is Intel's entry level Core i7 processor which runs at a stock speed of 2.66 GHz, not too far off from the high-end Core i7 965 model which runs at 3.2 GHz. While the high-end Core i7 965 sells for over $1,000, the Core i7 920 sells for a respectable $300, considering the performance that this chip is capable of with a little elbow grease. In terms of their basic hardware, they are the same chip underneath, but they simply run at different frequencies. While overclocking the Core i7 is a bit different compared to previous generation Core 2 processors, most of the same principles apply to these new systems.

So, we grabbed one of the new Core i7 920 processors off the retail shelf and decided to see how far we could clock it up. We want to give potential buyers an idea of what overclocking with the Core i7 is like, along with how much performance you'll gain, how to deal with heat, and how power consumption comes into play.

Core i7 920 Retail Box - Front

Core i7 920 Retail Box - Rear

There have been dozens of reviews on the Core i7 processor to date, and this article is not about going into the details of the new architecture. We're going to focus today on overclocking.  So here are some of the things we feel are the most important to potential new buyers when they are considering the purchase of a Core i7 system to overclock.

• Socket-1366 - Intel Core i7 processors run off a new physical socket with nearly double the pin count compared to Socket-775. While Socket-1366 looks visually similar to Socket-775, a direct comparison shows Socket-1366 being larger in every dimension, as Intel needs extra pins on the CPU in order to communicate with the processor's integrated memory controller, though they likely saved a few pins with the QPI serial interface versus their legacy FSB.
   
  The move to Socket-1366 means that all of your existing Core 2 gear, that being motherboards and cooling systems, will not work on a new Core i7 system. Compatible Socket-1366 motherboards and cooling systems are limited currently on the market in comparison to Core 2 based gear, but there are several good motherboards and cooling systems out there for overclockers. Some high-end cooling manufacturers are making adapters to retro-fit existing high-end coolers to Socket-1366, which could help ease the burden if you spent a lot on a Core 2 heatsink. Asus will also be shipping their upcoming P6T X58 motherboard with Socket-1366 and Socket-775 mounting holes for coolers, which should allow for some styles of Socket-775 coolers to work on the Core i7, although it will likely be difficult to guarantee universal compatibility.

  Socket-1366 Closeup

  Socket-1366 with Core i7 920 Installed

• Turbo Mode - Like previous generations of Intel processors, Core i7 processors are multiplier locked, meaning you can only adjust the system's clock multiplier downwards, not upwards, which limits easy overclocking. While Intel's high-end Core i7 Extreme Edition processors don't have this lock, the Core i7 920 processor we're dealing with today does have this lock.
   
  

  However, Intel has a slight "gift" with Core i7 processors in the form of "Turbo-mode", a new feature for the Core i7 lineup. When this feature is enabled (which can be toggled in the BIOS or through software), the processor can automatically detect when the processor's thermals are within specifications and can bump up the multiplier by one notch for additional performance. In the case of the Core i7 920, enabling Turbo mode boosts your stock clock speed from 2.66 GHz to 2.8 GHz.
   
  While Turbo mode isn't extremely helpful when it comes to high-end overclocking, it is another tool in the toolbox which overclockers can use to reach that final high clock speed they are reaching for. If you don't plan to overclock, enabling Turbo Mode is a simple, low-risk performance booster. If you're a dedicated overclocker, we would typically recommend disabling this feature to force consistent clock speeds.

Stock 2.66 GHz Speed

2.8 GHz with Turbo Mode Enabled

• Hyper-Threading is Back - A feature we haven't seen since the Pentium 4 days, Hyper-Threading, makes its face shown once again for the Core i7 series. Hyper-Threading allows each core to enable two simultaneous threads for processing. A quad-core processor with Hyper-Threading enabled will show to your operating system has eight cores. While impressive looking, Hyper-Threading will not give the performance of a true octa-core system, but in heavily multi-threaded applications, will give performance increases compared to the same system with Hyper-Threading disabled. Some older applications will show performance decreases with Hyper-Threading enabled, but at this point, these are typically few and far between. For most scenarios, we would recommend leaving Hyper-Threading enabled.
   
  However, when it comes to overclocking, users have an interesting dilemma. In our testing, we found that disabling Hyper-Threading typically led to slightly more stable overclocks on the high-end range. Which, in theory, makes a little sense, as the chip is working less hard in heavily threaded software. However, while we were able to obtain slightly higher clock speeds and retain stability, our benchmark numbers typically showed lower numbers compared to a lower-clocked processor with Hyper-Threading enabled.

Quad-core i7 Processor with Hyper-Threading Enabled

• 45nm Process - Intel's Core i7 processors are all manufactured on their latest generation 45nm manufacturing process. This aspect is largely responsible for the Core i7's improvements per clock in the areas of power consumption and heat production.  The 45nm manufacturing process also is one of the key reasons why Core i7 processors run at a very low core voltage level, only 1.1V out of the box. Typical overclocking with vCore ranges from 1.15V to 1.4V, with 1.5V being on the still-safe-but-pushing-it range. We typically saw no more additional clock speed benefits once we went above 1.4V, while doing so increased thermals and power consumption considerably.
   
  
• The Reference Clock - Core i7 processors are equipped with integrated memory controllers, much like AMD processors have had for years. As the front side bus is a connection between the CPU and the Northbridge memory controller, now that both of these components are integrated onto the same logic, the FSB is more or less extinct. As cranking up the FSB speeds have typically been the easiest way to overclock systems, getting rid of the FSB might appear to some as the death of Intel overclocking. Of course, this simply isn't the case. Core i7 processors drive their frequencies based off a reference clock set on the motherboard, which is user-adjustable. If you adjust the reference clock to a higher-rate, CPU and memory speeds rise with it, as their individual clock frequencies are based off multipliers of this reference clock.

Like all modern boxed Intel processors, the Core i7 920 is equipped with a large, circular cooling system. While it appears to be identical as their Socket-775 based Core 2 Duo/Quad coolers, the new Socket-1366 cooler is substantially larger. The cooler uses the same push-pin lock system along with a copper based and aluminum alloy thin-fins, and has three rows of thermal paste pre-applied. The fan sitting on top is an open-frame unit that has a Nidec fan with a PWM 4-pin fan connector.

Core i7 920 Retail Cooler - Top

Core i7 920 Retail Cooler - Bottom

The cooler is a reasonably good solution.  It's not particularly great when it comes to handling the thermal aspects of Core i7 processor, but it does its job without much fuss. It's easy to install, it's mostly quiet, and it can handle moderate overclocking with the Core i7 920. Keep in mind though, thermals can get very high with the retail cooling system, as we saw our Core i7 920 chip hit ceilings of 65°C during moderate overclocking.

Here's part of the problem. The stock Intel cooling solution has a circular copper base which only actually touches a good 65-70% of the Core i7 processor. The rest of the processor's heat spreader doesn't touch the heatsink, and such, as have less direct contact between the heat source and the heat dissipating device (the heatsink). After a round of overclocking tests, we removed the retail cooler from the motherboard, and here's a direct image showing which areas are actually touching each other.

The gray circles show where the processor and heatsink have a thermal contact point.

If you want to overclock and still keep thermals and noise levels in check, we would recommend going with a third party cooler. If you really want to reach for the sky, you can already go to a Socket-1366 water kit solution, as there are several options out there (at fairly high prices). We picked up Thermaltake's new Socket-1366-supported cooler, the V1 AX. This unit costs about $50, but allowed for significant decreases in thermals, even at low noise levels. The heatsink is equipped with four heatpipes, an array of thin-fin heatsinks and an internal 110mm fan, and the entire system is quite efficient. The system also has a base that covers the entire Socket-1366 core, which can be covered with your thermal paste of choice.

Proper Thermal Coverage

Thermaltake V1 AX Installed

When overclocking your Core i7 processor, you really don't need a ton of BIOS flexibility with your motherboard, you only need to tweak a few key variables in order to unlock this architecture's potential. We did our overclocking on an EVGA X58 X3 SLI motherboard, which is a terrific overclocking platform, although the controls needed can be found on most shipping X58 motherboards.

1) Reference Clock - Core i7 processors have a base reference clock of 133 MHz, which is the key driver of many of the performance aspects of any Core i7 system. Processor clocks, memory clocks and QPI clocks are all driven off of this clock speed, so upping this ups all of these clocks together. If you want to get your 920 processor to 4.0 GHz, you'll need to crank up your bus clock to 200 MHz and manipulate a few clock ratios.

In our tests, this was possible on air-cooling, but difficult to retain stability. Our highest fully stable range was in the area of 190-195 MHz FSB, which allowed us to run our Core i7 920 processor (2.66 GHz) in the 3.8-3.9 GHz range. Keep in mind, Intel's top of the line shipping 965XE model only runs at 3.2 GHz, meaning you are outperforming Intel's $1,000 flagship by a significant margin, on a $300 processor.

Reference Clock Adjustments

CPU, Memory, QPI Voltages

2) Memory - If you're upping the reference clock, be sure to check your memory timings as well. Core i7 systems run their DDR3 memory speeds as a multiplier of the overall reference clock, and these are timed to allow for 800 MHz - 1600 MHz overall DDR3 clock speeds. Depending on the speed of your memory modules, it's likely that you will need to drop this multiplier down, so that when you up the overall reference clock, you don't overdrive your memory beyond its capability. If you downclock your memory multiplier, it's likely you won't have to rely on upping your memory voltage in order to get a sizable overclock.

3) Voltages - Core i7 systems typically don't show massive overclocking gains with additional voltage being thrown at them, but we found that for heavier overclocking, voltage levels of 1.3V and higher were helpful in retaining stability, whereas levels of 1.4V and higher typically did very little to help our overclocking situation. If you're doing heavy overclocking, voltage levels of 1.5V have been attempted and don't appear to hurt the chip, although long-term reliability at this level is certainly an unknown.

Memory Frequencies

QPI Frequencies

4) QPI and PCI Express - If you want stability at overclocked levels, be sure to kick down your QPI speed (which is also derived from the reference clock) to its lowest multiplier, typically labeled 4.8 GT/s (though you can try other setting to reach a top QPI speed with stability), in order to keep this area in check in an overclocked scenario. If your motherboard lets you, manually set the PCI Express clock to 100 MHz as well.

What to (Really) Expect

While we have seen some overclocking teams reach 4.5 - 5.0 GHz using off-the-shelf Core i7 920 processors, these kind of speeds are highly unlikely using home-brewed air-cooling or water-cooling setups. In order to reach these heights, you likely need to go into the LN2 or heavy duty water cooling setup areas. Here's what we think is possible for most end users out there using standard air-cooling systems.

So, with a little grunt work, we were able to establish a stable overclock to 4.0 GHz on our Core i7 920 processor, maxing out at 190 MHz FSB using a 21x multiplier (Turbo Mode). This represents a 50% boost in clock speed with absolutely no price increase. However, while overclocking does deliver better performance for free, it does come at a price, power consumption. All of our overclocked systems were using a 1.325V vCore and 1.7V vDIMM. Here you can see how much upping your processor speed also ups your power bill.

As you can see, under full load, there is a sizable difference in terms of power consumption between our stock speed chip and our highly clocked and over-volted chip. This 50% boost in clock speed also requires 48% more power under full load. While our systems are still fairly low in terms of overall power usage for the performance which is offered, this is something to keep in mind when you start to unleash your 920's overclocking options.

Test System Details Specifications and Revisions

• Intel Core i7 920 Processor (2.66 GHz, 8 MB L3, 20 x 1333 MHz Clock)
• 3 x DDR3-1333 MHz Memory Modules, Triple Channel, 6 GB Capacity, CAS 7-7-7
• 1 x eVGA X58 X3 SLI Motherboard, Intel X58 Chipset
• 1 x Nvidia QuadroFX 4800 1.5 GB Graphics Card
• 1 x Western Digital VelociRaptor 150GB 10,000 RPM SATA-II Hard Disk
• 1 x Plextor DVD+/-RW Serial ATA Optical Drive
• 1 x Corsair HX620W 620W Modular Power Supply
• Microsoft Windows Vista Ultimate x64 Edition

PCMark Vantage - Synthetic System Performance Higher Scores Are Better

3DMark Vantage - Synthetic Gaming Performance Higher Scores Are Better

While upping our Core i7 920 to 4.0 GHz represents a big boost in terms of overall clock rate, this doesn't immediately translate into huge performance increases. With this much CPU power at your disposal, other aspects of your system configuration quickly become bottlenecks. Our GPU-limited 3DMark Vantage test doesn't show huge gains, as our 1.5 GB equipped QuadroFX card became the bottleneck, which shows what kind of power we're dealing with on the CPU level. However, in the specific CPU benchmark, we see sizable performance increases with each overclocked level.

Crysis CPU Benchmark - Real World Gaming Performance Higher Scores Are Better

Cinebench 10 CPU Benchmark - Synthetic 3D Rendering Performance Lower Times Are Better

Crysis once again shows how gaming environments will likely be bottlenecked by a graphics card in order to deliver top-tier performance. Though certainly there are very tangible gains here. Rendering-focused Cinebench showcases solid decreases in rendering time as the Core i7 920 processor increases in overall clock speed.

Valve Software Particle Benchmark - Synthetic CPU Performance Higher Scores Are Better

Valve Map Build - Real World Gamedev Map Build Time Lower Times Are Better

Multi-core enabled game engines can see huge performance increases with an overclocked Core i7 processor. In multi-core particle performance, overclocking the Core i7 920 processor to 4.0 GHz delivered a 47% boost in speeds, scaling almost perfectly with the higher speed overclocks. Our overclocked chip was also able to build a sample map 34 seconds faster compared to the chip at stock speeds.

Judging just the processor alone, the Core i7 920 delivers excellent performance at a respectable price range of about $250 - $300. Even at stock speeds, it's a pretty good value, but when you throw overclocking into the mix, the 920 becomes a much more attractive option. Suddenly, with a little work, you can get substantially higher clock speeds compared to what Intel has on the market today, heavily outpacing the $1,000 Core i7 Extreme Edition chip at 3.2 GHz. This translates to a huge amount of computing power at a very low price.

However, when you factor in the entire platform upgrades needed to move to the Core i7, things get slightly less exciting. In order to move to the new CPU, you need an X58 motherboard, which can run from $275 - $350 in most scenarios. If you don't have DDR3 memory, moving to a new 3GB or 6 GB pack (for triple-channel memory support) can add another few hundred dollars on top of that. If you want to really overclock, you'll want a third party cooler too, which can lop on another $50. Things quickly add up in this new territory, but overall, most can make the move to the Core i7 for under $750 total in most scenarios.

At 4.0 GHz clock speed, the Intel Core i7 920 delivers a great computing experience. While it's tough to tell a difference with small tasks at the stock speed of the 2.66 GHz Core i7 920 processor, the difference in heavy application and gaming performance was immediately noticeable. The system felt slightly snappier overall, although considering the Core i7 920 chip is already pretty fast as is, you'd likely only notice the differences when you really start to tax the system.

However, as a "free" upgrade, there is no denying overclocking is a good value. With a nice third party cooler, you can still keep the chip cool and quiet, even at these higher clock rates. If you have a good motherboard with proper memory module support, you can make sure your clock speeds and timings are in-line, leading to very little chance of system instability. Getting the chip up and running at fairly high frequencies is quite easy to do, as well, if you know exactly what to tweak and by how much. Even though a lot of things have changed about the Core i7 platform compared to the Core 2 series, the overall overclockability of the chips haven't changed much. In fact, these first Core i7 chips appear to be overclocking surprisingly well so early on after its debut, which is great for first-round buyers.

Even better, the higher-binned Core i7 processors, the 940 and 965XE, are overclocking exceedingly high, as well. While the Core i7 920 is definitely the value leader, throwing a few hundred dollars here or there might allow you to push past 4.0 GHz a little easier compared to the 920, although we doubt you'll get that much more to justify the price tag increase. We're also now starting to see the first wave of less-expensive X58 motherboards hit the market, hoping to crack the sub-$300 price point. In addition, DDR3 memory prices are becoming more reasonable every day, so it looks like a pretty solid time to make an upgrade move, especially if you're mode of burning off all those holiday gift cards.

Easy Overclock to ~3.5 GHz Most Should Hit 4.0 GHz (with work) Performance Scales Well Per Clock	Sizable Power Needs at High Clock Speeds Stock Cooler Struggles at 3.5 GHz+ Levels Expensive Motherboards Required