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Power, In Depth: CPU Health at 4.8 GHz

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

The previous page was a red flag warning us that our processor didn't have much headroom left. And yet, we pushing on, shooting for 4.8 GHz across all eight cores. Because this meant hitting 1.4 V and risking the health of our CPU, we didn't bother repeating the experiment using six cores. In a real gaming machine, you probably won't want to spend much time up where we're operating.

Core Voltage

An average of 1.38 V is the end of the line. And even then, there's a chance we might kill our Core i7-5960X inadvertently.

Power Draw

The voltage regulators struggle to keep pace. We see extreme fluctuations for the first time as our CPU hits its wall often. Throttling under load just can't be helped.

Even at idle, the high voltage leaves its mark.

Power consumption doesn't increase much at this point, mostly because the Core i7 throttles almost continuously at 10 to 12 percent. This is as far as you go with water cooling. Did you ever think you'd see an Intel processor chewing up 206 W on its own (or 250 W from the voltage regulator)? Now you have.

Power Consumption
Average, Idle
Maximum, 100% Load
Average, 100% Load
CPU 12 V In
27 W
302 W
250 W
CPU Package
21 W
218 W
206 W
VRM Loss
6 W
84 W
44 W

Temperatures

Thermals are through the roof. A water temperature reading of 38 degrees Celsius is staggering in its own right, and there's no way to get it lower, even with the cooler's fans manually set to their highest speed. The core temperature is visibly capped at 88 degrees Celsius, meaning there's a lot of throttling going on.

Let’s take one more look at the time-lapse video, which shows (for the first time) the CPU heating up faster than the voltage regulation circuitry underneath it.

Temperature T
Idle
Maximum, 100% Load
Average, 100% Load (Heated Up)
Core
28 °C
88 °C
78 °C
Package
29 °C
68 °C

Water (In / Out)
24 °C / 28 °C
38 °C

VRM
34 °C
69 °C

A Comparison of Frequency, Temperature, and Power Consumption

Our findings are summarized in the graph below, which primarily shows one thing: overclocking Intel's Core i7-5960X up to 4 GHz isn’t a problem. Between 4 and 4.5 GHz, power consumption and thermals rise much faster though. The top of that range (and the voltages required to achieve stability) represents the highest you can hope to go on air or water without worrying about your CPU. And even then, I wouldn't be so aggressive with a processor I wanted to last.

The absolute end of the line is 4.8 GHz, where the -5960X goes into self-preservation mode.

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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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