As we know from our performance tests, video transcoding is one of those load types that scales as the number of computational cores in the system increases. Moreover, this load causes the CPU to heat up pretty seriously and consume a lot of power.
Taking into account everything that has been just said, it is not surprising that the power consumption of overclocked systems is significantly higher than that of systems working in their nominal mode. We have just seen in our preliminary power consumption tests under maximum load that during overclocking the CPU current may more than double. Therefore, when we increase the CPU frequency and slightly correct its voltage, 30-40 W higher power consumption is considered normal. Only quad-core Nehalem processors, Core i7-950 and Core i7-860, do not fit the profile. Overclocking causes a much greater power consumption increase of 80-90 W in systems with these processors.
In terms of processor load final rendering in 3D modeling suites is very similar to video transcoding. This task can also be easily paralleled and loads the CPU pretty heavily pushing its power consumption and heat dissipation to the maximum.
It is quite logical that the results of our power consumption measurements are very similar to those that we obtained during video transcoding. I would only like to point out the fact that in this case power consumption is still a little lower than in the previous tests.
Our preliminary tests showed that the power consumption increases significantly during overclocking only when we need to raise the processor Vcore to ensure system stability. In this case we see actual proof of this conclusion in real examples. When we overclock our processors at their nominal core voltage we add maximum 10 W to the nominal system power consumption. Once we attempt to get our CPU to work at its maximum possible clock speed by raising Vcore and Vtt voltages, total system power consumption may increase by a few tens of watts. Moreover, strange as it might seem, but CPUs with more computational cores get more power hungry, Core i7-950 and Core i7-860 from Nehalem generation being the most energy-demanding.