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

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

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 Consumption
Average Idle
Maximum, 100% Load
Average, 100% Load
CPU 12 V In
22 W
165 W
146 W
CPU Package
18 W
128 W
124 W
VRM Loss
4 W
43 W
23 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 T
Idle
Maximum, 100% Load
Average, 100% Load (Heated Up)
Core
27 °C
57 °C
48 °C
Package
29 °C
48 °C

Water (In / Out)
24 °C / 27 °C
32 °C

VRM
34 °C
47 °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 Consumption
Average, Idle
Maximum, 100% Load
Average, 100% Load
CPU 12 V In
21 W
137 W
115 W
CPU Package
17 W
105 W
101 W
VRM Loss
4 W
32 W
14 W

Temperatures

Here are the temperatures under load:

Temperature T
Idle
Maximum, 100% Load
Average, 100% Load (Heated Up)
Core
27 °C
53 °C
46 °C
Package
28 °C
44 °C

Water (In / Out)
24 °C / 27 °C
31 °C

VRM
34 °C
45 °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.

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  • 1 Hide
    wireframed , 29 August 2014 18:24
    Well, that's a bit of a mixed bag. The review was nice, though.

    Personally, the 3DS and After Effects benchmarks were of most interest, since they are what I spend most of the CPU time on. (3DS in particular, right now I'm logging dozens of CPU hours a day on 3DS alone). It's pretty clear that unless the platform costs of Haswell-E are much higher than IB-E, going with the old won't make sense. The 5930k beats the 4960X. which is at least 50% more expensive.

    I've been waiting forever for an upgrade to my i7 930 based workstation, and I didn't feel like jumping on an IB-E a couple months before a brand-new HEDT platform is released.

    I had hoped Haswell-E would be a bit more impressive, but OTOH, investing in a DDR4 platform now might be a good idea, given my workstations typically have 3-4 years in them. At the very least, a drop-in upgrade to Broadwell-E would be nice to have as an option.

    Now to see how big a pounding I'll take in Denmark for X99/DDR4/Haswell-E... :o 
  • 0 Hide
    haider95 , 30 August 2014 17:56
    sweepstakes only for US users?
  • 0 Hide
    Robi_g , 30 August 2014 22:06
    Text on the competition PC says EVGA motherboard, but the picture has an ASrock one.
  • -1 Hide
    Robi_g , 30 August 2014 22:06
    Text on the competition PC says EVGA motherboard, but the picture has an ASrock one.
  • -1 Hide
    Robi_g , 30 August 2014 22:07
    Text on the competition PC says EVGA motherboard, but the picture has an ASrock one.
  • -1 Hide
    BigBadBeef , 2 September 2014 05:45
    I am an enthusiast and even I say "NO" to this marketet prototype. I will not participate as Intel's guinea pig.
  • 0 Hide
    LePhuronn , 4 September 2014 14:59
    Although I agree with the logic behind the "smart choice" at the end of this article, in the real world the PCI-E lane count for gaming is a moot point. X99 is NOT a gaming platform. It is a workstation and productivity platform. Regardless of how much you hobble your CPU, you're still paying £300 for the motherboard and £400 for comparatively paultry amounts of RAM, so the price of overall Haswell-E adoption is very high.

    Therefore anybody who's going to load up on GPUs enough to worry about PCI-E lanes will have sufficient money to drop in a 5960X on principle. Anybody who's adopting X99 for productivity purposes will not skimp on core count and also go 5960X, especially considering they're likely to go at least 32GB RAM and therefore shelling out a lot of money. Those producing on CUDA cards may not even go X99 at all because 1150 Haswell has more than enough power to run the software. Folders and CUDA Miners similarly will want all GPUs running at full tilt so will likely invest in the 5960X to get all the PCI-E lanes.

    So really, the only "smart choice" is 5960X or don't go X99 at all.
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