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Intel Core i7-5960X, -5930K And -5820K CPU Review: Haswell-E Rises

Power, In Depth: Eight and Six Cores at 4 GHz

Core Voltage

Overclocked to 4 GHz, our Core i7-5960X's core voltage is now 1.110 V. This time around we're optimizing it manually to minimize power consumption and temperature.

Power Draw

The following chart contrasts the VRM's measurement with our reading at the EPS connector, in addition to power losses due to the voltage regulation circuit.

A reading of 18 W at idle is identical to what we just saw at 3.5 GHz. However, the increase to 124 W under load shows that the eight-core configuration running at 4 GHz is starting to pull quite a bit more power from the wall.

Still, these figures are within reason considering the performance you get in return.

Power ConsumptionAverage IdleMaximum, 100% LoadAverage, 100% Load
CPU 12 V In22 W165 W146 W
CPU Package18 W128 W124 W
VRM Loss4 W43 W23 W

Temperatures

The temperatures at idle don't increase. And as clock rate goes up, the difference between each core's minimum and maximum temperature becomes more pronounced, too.

It’s time for a look at the time-lapse video.

Temperature TIdleMaximum, 100% LoadAverage, 100% Load (Heated Up)
Core27 °C57 °C48 °C
Package29 °C48 °C
Water (In / Out)24 °C / 27 °C32 °C
VRM34 °C47 °C

Six Cores At 4 GHz

Again, we want to try the same thing using six cores to estimate how the Core i7-5930K or -3820K might behave.

Core Voltage

Registering 1.100 V, there’s barely any difference in CPU core voltage between the six- and eight-core models.

Power Draw

Disabling two cores yields a reduction in power consumption to 17 W at idle (21 W if you count the VR) and 101 W under load. That's notably less than the eight-core configuration.

Power ConsumptionAverage, IdleMaximum, 100% LoadAverage, 100% Load
CPU 12 V In21 W137 W115 W
CPU Package17 W105 W101 W
VRM Loss4 W32 W14 W

Temperatures

Here are the temperatures under load:

Temperature TIdleMaximum, 100% Load Average, 100% Load (Heated Up)
Core27 °C53 °C46 °C
Package28 °C44 °C
Water (In / Out)24 °C / 27 °C31 °C
VRM34 °C45 °C

Our eight- and six-core setups increase about 20 W when we overclock to 4 GHz. It's easy to see that we're operating Haswell-E above its sweet spot. Nevertheless, you should be able to hit a stable overclock at comparable performance levels using a big heat sink. Just be sure you have a high-end cooler and a chassis with good airflow.

Chris Angelini
Chris Angelini is an Editor Emeritus at Tom's Hardware US. He edits hardware reviews and covers high-profile CPU and GPU launches.