The Phenom is surprisingly overclocável for a quad-core. Besides the use of the technique with 45 nm SOI, the great secret is the fact that it is a quad-core native, unlike the Core 2 Quad,where we have two dual-core processors communicating via the FSB. Using a good cooler, it is difficult to obtain from 3.5 to 3.8 GHz overclock a Phenom X3 720 or an X4 920, which makes them quite affordable options for those who want a high-performance PC. If you're getting now, read the post with the basics of overclocking.

As with the Intel i7 processors, the AMD-based architecture K10 (Phenom, Athlon and Phenom X2) using a reference clock that is used to generate 4 independent frequency:

Frequency processor: The processor clock is derived from a multiplier, and the processors that use the FSB. As usual, the multiplier is locked for more (except for the Black Edition processors), making it necessary to increase the reference clock to overclock.

Frequency North Bridge (North Bridge): This is the frequency of the memory controller and L3 cache (if present), which according to the model of the processor can be 1.8 or 2.0 GHz frequency of the North Bridge is released from frequency of the processor and the rest is adjusted by a multiplier separately, which differs from the main multiplier is unlocked on all models.

Frequency of Memory: How the memory controller is part of the processor, the memory frequency is also affected by increasing the reference clock, which can also be offset by a reduction in the multiplier.

HyperTransport Frequency: HyperTransport controls all communication with the CPU North Bridge. As in the case of the North Bridge, the nominal frequency in the Phenom and Phenom is 1.8 or 2.0 GHz and is obtained from the reference clock. The frequency of the HyperTransport not have a significant impact on performance, so it is better to keep it at a frequency close to the nominal to prevent it from becoming a limiting factor in overclocking. Another rule is that the frequency of HT may be equal to or less than the North Bridge, but never more.

The base frequency is always 200 MHz (since the time of the Athlon 64) and other frequencies are obtained by multiplying. In a Phenom X4 920, for example, have a frequency of 2.8 GHz for the processor (14x multiplier), 1.8 GHz to North Bridge (multiplier 9x), 800 or 1066 MHz effective memory for (multiplier of 2.0x or 2.66x) and 1.8 GHz HyperTransport (multiplier 9x).

By increasing the reference clock, all frequencies are increased simultaneously, which makes you almost always have problems with memory, with the North Bridge with HyperTransport or much before reaching the ceiling of the processor.

The exception is the series of processors Black Edition, which sold a little more expensive just because they have the multiplier unlocked, which greatly simplifies things, since you can simply increase the multiplier, without moving the base frequency. For other processors, the solution is to adjust the frequency through the multiplier, reducing the values increase as the reference clock.

By using 240 MHz for Phenom's example, you have 3:36 GHz processor, 2.16 GHz for the North Bridge and the HT and 960 MHz for memory (when using DDR2-800).

The processor will not have major problems to operate at that frequency, but the 2.16 GHz are higher than supported by Hyper Transport, which probably will make the overclock is unsuccessful. However, by lowering the HT multiplier to 8x (resulting in a frequency of 1.92 GHz, and closer to the original 1.8 GHz) processor is operating steadily:

Unless the modules used to have a good tolerance, and 960 MHz for the memory can also be a problem. As you increase the base frequency, you will slowly approaching the ceiling of the modules, to the point where they begin to show errors. When this happens, you have no choice but to reduce the multiplier of memory, as well as in the case of HT.

For its DDR2-800 work with a base frequency of 300 MHz, for example, you will most likely have to reduce the multiplier from 2.0 to 1.33. In this example, the final frequency will remain the same (1.33 x 300 x 2.0 MHz = 200 MHz), but there are many cases where you need to choose between limiting the overclock or use a slightly lower frequency to memory. When using a base frequency of 285 MHz, for example, the modules would work only 759 MHz

In many boards, you will not find the option to directly adjust the multiplier, having in place an option to select the type of memory used (DDR2-553, DDR2-800, DDR2-1066, etc..) Where the BIOS automatically sets the multiplier for the frequency indicated.

Then we have the frequency of the North Bridge, which also has a significant impact on performance, because it determines the frequency of the L3 cache and integrated memory controller. Although the North Bridge does not provide an overclocking margin as large as the rest of the processor, you can get from 2.4 to 2.6 GHz by adjusting the multiplier according to the base frequency used. It may seem little, but it is enough to get a gain of 3 to 4% in many applications.

Unfortunately, there are cases of motherboards that do not offer the option to adjust the multiplied the North Bridge separately from the CPU multiplier. In such cases, the overclocking has been limited, because you are restricted to 20 or 30% increase supported by the North Bridge, even though the processor can go further. In such cases, a Black Edition might be a better choice as it can increase the CPU clock by multiplying without relying solely on increasing the frequency base.

In addition to the multiplier, we also have the issue of tensions. The default value varies depending on the model of the processor, but the maximum voltage recommended for any Phenom 45 nm is 1.55V, regardless of the model. The reason is simple: all the processors are produced in the same production line and using the same process. They are selected according to the maximum clock rate and the minimum operating voltages, but the physical characteristics are the same.

In addition to the processor voltage, which is rice with beans, we also have memories of the tension and strain of North Bridge, which although part of the processor, using a specific strain. As with the processor, a small increase to help obtain higher frequencies.

For best results, it is important to turn off Cool'n'Quiet support in Setup, since reductions in tensions and fluctuations caused by changes in processor frequency just reducing the scope for overclocking.

Another option is to use the AMD Fusion (http://game.amd.com/us-en/drivers_fusion.aspx) in conjunction with the Overdrive to create a profile, enabling the overclocking (or increasing the frequency to the maximum) to run games or other specific applications. This is a good solution in terms of efficiency, since you can use the default frequency in the rest of the time, saving energy and preserving the life of the processor.

Another option that reduces the margin for overclocking is to "Spread Spectrum", which can also be disabled through the Setup. Its function is to create small fluctuations in operating frequency of the processor (in order to meet the electromagnetic emission standards of some countries in Europe), which reduces the ceiling to overclock the processor's MHz

The "Advanced Clock Calibration (ACC Technology) obtained as small gains in overclocking Phenoms old, made no difference in the Phenom (where improvements have been incorporated directly into the firmware), so no point in wasting time with it. The only function was to unlock the fourth core in compatible cards.

To simplify things, the ideal is to start using lower multipliers for memory, HT and North Bridge and get overclocked the processor by increasing the base frequency. After you find the maximum clock of the processor with the default voltage, switch to a second round of tests, using small increases in tension (without going over 1.55V). Upon reaching the maximum frequency of the processor, 100 MHz step back and you will arrive at a moderate rate, with a good margin of stability.

Determined the frequency of the processor, go to step 2, increasing the multiplier from memory and the North Bridge (one at a time) until you find the maximum supported by the pair. As I said, it makes little sense to increase the frequency of HT (as the performance impact is minimal), it is best to simply use a multiplier that results in a frequency close to 2.0 GHz.