Measuring electrical quantities of PC enclosure is a curious task. It's particularly interesting and informative to measure platform's consumed power and energy consumption, two different things people tend to mix up. Let's clear the definitions first: power is the rate at which energy is produced or consumed (in our case). Power is measured in watts, while energy is usually measured in kilowatt hour (watt hour in our case). You might also want to read the article on Wikipedia.

Tasks one can load a computer with differ based on how much work is done in a unit of time and how this rate changes over time.

Judging by the amount of work done, we can say there are 'constant' and 'variable' tasks. Some of the constant tasks are regular video playback, data compression/decompression, video encoding and transcoding. One example of a variable task is games, where the amount of work done depends on PC hardware and may differ greatly. In this last case, measuring energy consumption as such is kind of meaningless, because we'll be measuring how much energy is spent on different amounts of work.

Judging by how the rate of work done changes with time, we can say that some tasks depend on PC hardware performance and some don't. An example of a hardware-independent task is video playback. An example of a hardware-dependent task is data compression (the more powerful the PC is, the faster data compression will be completed).

The point of all this is that we plan to create a test method that would include benchmarks of all the types described above. Today, however, we'll conduct a 'pilot' testing with a limited number of benchmarks.

For this review, we measured consumed power and energy consumption of four configurations based on the same testbed and four different CPUs belonging to two platforms: Intel Core i7-2700K (Sandy Bridge) and Intel Core i7-3770K (Ivy Bridge), Intel Core i5-2400 (Sandy Bridge) and Intel Core i5-3450 (Ivy Bridge).

For each pair, we chose most similar CPUs (except for the platform, of course). This allows us to compare the old and new processors and see how electric quantities change in a transition from Sandy Bridge to Ivy Bridge.

In our previous tests of Intel Core i7-3770K, we found out that Ivy Bridge CPUs were about 10%-15% faster than Sandy Bridge counterparts. The TDP of the new CPUs was lower by 18W at that. This only makes our comparison more interesting.

Testbed

• ASRock Z77 Extreme 6 motherboard
• Corsair Dominator DDR3 1333 MHz 2x2GB RAM
• Corsair AX750 power supply unit
• Power monitor (in Russian; we'll translate it if you need it)
• Boxed CPU cooler for LGA 1156
• Intel X25-V SSD drive

Note: We measured the consumed power and energy consumption of the rig consisting of a motherboard, CPU, cooler, and RAM. Storage devices were not considered. The published results were obtained by measuring amperages and voltages on the +3.3VDC, +5VDC, +12VDC, and ATX12V rails.

Benchmarks

• Intel Linpack Benchmark x32 — a command-line linear equation set solver and one of the most effective tools for testing CPU stability.
• Furmark — a stress test utility for graphics subsystems.
• Windows Media Player 12 playing a Samsung Demo BDRemux (1920x1080, H.264, High@L4.1, 20 Mbps avg., 35 Mbps max.).

Notes: In the idle mode, the CPUs were only loaded by background OS processes and Microsoft Security Essentials. The K Series Intel CPUs were tested in both the reference mode and while overclocked to 4000 MHz (multiplier tune-up only).

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