Performance per watt

This rate is typically measured by performance on the LINPACK benchmark when trying to compare between computing systems: an example using this is the Green500 list of supercomputers.

The Fujitsu FR-V VLIW/vector processor system on a chip in the 4 FR550 core variant released 2005 performs 51 Giga-OPS with 3 watts of power consumption resulting in 17 billion operations per watt-second.

Most of the power a computer uses is converted into heat, so a system that takes fewer watts to do a job will require less cooling to maintain a given operating temperature.

As of June 2016[update], the Green500 list rates the two most efficient supercomputers highest – those are both based on the same manycore accelerator PEZY-SCnp Japanese technology in addition to Intel Xeon processors – both at RIKEN, the top one at 6673.8 MFLOPS/watt; and the third ranked is the Chinese-technology Sunway TaihuLight (a much bigger machine, that is the ranked 2nd on TOP500, the others are not on that list) at 6051.3 MFLOPS/watt.

[6] In June 2012, the Green500 list rated BlueGene/Q, Power BQC 16C as the most efficient supercomputer on the TOP500 in terms of FLOPS per watt, running at 2,100.88 MFLOPS/watt.

[10][11] As part of the Intel Tera-Scale research project, the team produced an 80-core CPU that can achieve over 16,000 MFLOPS/watt.

Microwulf, a low cost desktop Beowulf cluster of four dual-core Athlon 64 X2 3800+ computers, runs at 58 MFLOPS/watt.

Graphics processing units (GPU) have continued to increase in energy usage, while CPUs designers have recently[when?]

[20] With modern GPUs, energy usage is an important constraint on the maximum computational capabilities that can be achieved.

Since GPUs may also be used for some general purpose computation, sometimes their performance is measured in terms also applied to CPUs, such as FLOPS per watt.

Likewise, systems that spend much of their time in standby or soft off are not adequately characterized by just efficiency under load.

[26][27] Energy required for climate control of the computer's surroundings is often not counted in the wattage calculation, but it can be significant.