Old school overclock

AMD with the new FX CPUs did not want to betray the overclocking enthusiasts, especially extreme, giving much satisfaction to those who want to engage in this practice, despite a bit disappointing performance. Already before the official presentation, AMD experts had recorded the frequency record, using an FX-8150 CPU cooled with liquid helium. This record was recently beaten with the same top of the range AMD CPU, reaching the incredible frequency of 8585 MHz! The AMD FX CPUs, if properly cooled, tolerate very high voltages, above 2V.

The temperatures are generally the main hurdle to reach high frequencies. Extreme cooling systems are especially useful on these CPUs, unlike what is seen with Sandy Bridge and Sandy Bridge-E CPUs, that even lowering the temperature below freezing, can not earn much room for overclocking.

As for overclocking for daily use, overclocking margins are pretty good, allowing you to reach without too much difficulty 4.6/4.8 GHz and 5 GHz in some cases; in all cases, however, is necessary a good cooling system, since this CPU consumption is very high at full load, especially if you apply a consistent overclock and overvolt. With air cooler of modest size obviously the overclocking margin decreases.

The overclocking of the FX CPU is made in rather than classic mode. We can adjust several parameters: the bus frequency (HTT), the CPU multiplier (FX CPUs are unlocked), the multiplier of the Hyper Transport link and Northbridge multiplier. The voltages of greater interest for the overclock are obviously the Vcore and partially the CPU-NB.

In general, the easiest way to overclock is to increase the CPU multiplier, but the most profitable, both in terms of performance and frequency, include maximizing the bus (HTT).

Using the press kit that AMD has given us and in particular the Asus motherboard you can do overclocking effectively. Asus ROG series has introduced the RC TweakIt software that greatly facilitates the task of overclocking our components. Since the 'FX-8150 is a 32nm CPU, you can easily reach the frequency of 4.5 GHz. More difficult will be overcoming the frequency of 4.8 GHz with air cooling systems; the behavior will depend very much on the goodness of our CPU. The first thing you need to do is disable the various energy-saving technologies and set the parameter of the Load Line Calibration on high to stabilize the supply voltages under overclocking. Here are two screenshots of the BIOS in which these parameters are present.

After this, the next step is to enable communication by moving the micro switch selector to ON to allow the connection of the RC TweakIt application that we installed on a laptop/external PC and connected to the motherboard via the white USB cable supplied with. Here is a macro of the position of the switch on the PCB of the Crosshair Formula V and the user friendly software interface provided by the RC TweakIt software provided by the Crosshair Formula V.

We went up in frequency step by step by acting both on the voltage supplied to the processor (Vcore) and both on the bus (HTT). Setting as a starting point, from BIOS, the multiplier to x23, we climbed up to get the results shown below. Of course, an eye should be kept at temperatures, but the 5GHz for those on a liquid cooling are easily accessible if the processor is cooled by a cooling system designed for this purpose.

Following, with our overclocking team we decided to go further with the frequencies and operating voltages. This is of course possible using extreme cooling. To this end, we used a Cascade phase change by Dimas: this system allows you to get several degrees below zero °C, reaching even -120 °C without load. Below you can see the various screens that we performed with this system, pushing well beyond the 6 GHz for some tests.

To achieve the 7 GHz are required cooling systems with liquid nitrogen or liquid helium, that we have not been able to experience due to lack of time.