In our articles we always talk about processor overclocking potential and even benchmark overclocked systems. However, it is important to understand that CPU overclocking is not only an affordable way of increasing the system performance without any additional investments. Although overclocking has gone down to the consumer level these days and doesn’t require the user to possess any specific skills or knowledge, there are a lot of hidden obstacles hiding behind simple adjustment of the BIOS Setup parameters. Today we tried to reveal one of these obstacles that many computer enthusiasts face: CU overclocking increases its power consumption. Moreover, it is fairly easy to push the processor power consumption far beyond its calculated TDP and everyone should be prepared for that. Processor cooling system should be able to dissipate a lot of heat. Processor voltage regulator circuitry on the mainboard should have more than twice the “current reserve” available. And the system power supply should have at least 1.5 times the power capacity of the system working in its nominal mode under maximum load.
So, it turns out that you can’t really overclock without any additional investments. Moreover, you have to make them beforehand, even when you are just putting the system together. And unfortunately, we can’t really neglect them: we always experience power consumption increase during overclocking, and it doesn’t matter what platform and what processor we have. However, we don’t want to overestimate the power consumption increase during overclocking, either. As our tests showed, there is always a cheaper” alternative.
If we look at the power consumption graph during overclocking of almost any processor, we will see, that it consists of two very characteristics parts. The first one is a relatively flat part of the graph that increases slowly, and the second one is the part where the graph starts growing very abruptly. The turning point on this graph doesn’t occur spontaneously, but happens at a very specific moment of time – namely, when it comes to raising the CPU Vcore. In other words, you don’t need t fear that the processor power consumption will skyrocket, until there is real need to adjust any of the system voltages to ensure stability. As for overclocking at nominal voltages, even though it doesn’t allow you to hit very high performance levels, it is not so useless after all. For example, several processors from our today’s test session worked at 3.6-3.8 GHz frequency and at their default core voltage. And by the way, overclocking like that doesn’t really stress the cooling and power systems in any way, but also allows to save some power when working on some resource-hungry tasks.
In conclusion I would like to stress that when you overclock different processors up to about the same frequencies, they still consume different amounts of power. It is quite obvious that quad-core processors consume more power during overclocking. However, this is not the only dependence that we observed. Namely, LGA775 CPUs proved to be the most energy-efficient during overclocking. Also, Athlon II processors demonstrated very modest power appetite. I would also like to point out Core i3-540 processor. This is the only CPU tested today that is manufactured using the most advanced 32 nm technological process, which had to affect its results. It obviously consumed the least power of all at its nominal frequency as well as after overclocking.
As for the power consumption “leaders” they are Phenom II and Core i7 CPUs. Overclocking these processors causes a much more substantial increase in the system power consumption than in all other cases. And I am not talking only about the absolute values here. Even in relative prospective, overclocking these CPUs may cause about 4—50% increase in system power consumption. Therefore, if you are looking for a suitable power supply for an overclocker system, make sure that you will have at least that much capacity in reserve.