Overclocking a Core i7 920

If you’ve purchased a new Intel Core i7 920, you’ve got your hands on one of the most powerful CPUs available – and contrary to early reports, it is possible to overclock this component and get even more processing power out of it!

Overclocking has recently progressed from the secret black arts of hardcore techies over the past few years and is now an accepted part of building a PC. Motherboards and video cards come equipped with overclocking software, and if there is a possibility of pushing a CPU to match the speed of a more expensive alternative then surely it is worth it?

Veteran overclockers will need to learn some new rules with the Core i7 processors however – Intel have changed the rules with this new architecture.

Core i7-920 are effectively “locked” – certain components of the processor that can be adjusted in the Core i7-965 are out of bounds on the 920. This doesn’t mean overclocking isn’t possible, however – in fact if you’re a beginner this is a great CPU to start on.

Booting your Intel Core i7 powered PC straight into the BIOS will reveal no mention of a Front Side Bus (FSB) – the architecture that has linked the CPU to the memory controller since the first PCs were made has now been discarded, with the CPU now hosting the integrated memory controller.

Replacing the FSB is the Base Clock (also known as the Host Clock) – as with the old FSB, this is the main reference point for overclocking, and will require adjusting in order to increase it over 133 MHz.

Joining the Base Clock on the CPU are the usual suspects such as the cache – all none core components of the CPU are referred to as the “uncore” and this has an effect on how you overclock, depending on your Intel Core i7 CPU.

If your processor is the Extreme Edition, you can overclock the core and uncore at separate rates as it is unlikely you will need the uncore to be functioning as fast as the main core. Non-Extreme Edition Core i7 CPUs however cannot be set to different rates in this way.

You cannot successfully overclock Core i7 processors without a pen and paper and a calculator – you’ve got some multiplication to complete!

If you’re using a Core i7-920 with a multiplier of 20, calculating this against the default Base Clock frequency displayed in the BIOS of 133MHz will result in a CPU speed of 2.66GHz. Meanwhile the default memory multiplier of 8 will result in a speed of 1066MHz – however this requires the uncore speed to be twice as fast, at 3.2GHz.

For instance if you want to push a 2.66GHz Core i7-920 upto 3.5GHz you would do this by upping the base clock from 133Mhz to 166, and checking that the BIOS has adjusted the uncore and RAM multipliers. All other components of the CPU and motherboard should be automatically upped by the BIOS.

Cooling is vital to keep a lid on the integrity of your system by managing the heat generated by an increase in voltage. When overclocking a Core i7 CPU, you need to keep the core voltage below 1.25v, the uncore below 1.45v and the system RAM under 1.65v. To achieve this and manage the temperature, remember that you will also need a decent PSU. You should be looking at a unit outputting around 1000W.

Getting an overclock rate you are happy with then requires some testing. Once you can get somewhere near your target and boot your PC into Windows, use a tool such as Prime95 to test stability.