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Power Draw: Test System And Methods

PowerColor PCS+ R9 290X Review: Cool, Quiet, And Priced Right
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Test System and Measurement Method

We partnered up with HAMEG Instruments (Rohde & Schwarz) to implement a state-of-the-art test system for precise, short interval power and performance measurements.

Only modern lab instruments can keep up with the challenges that AMD’s Power Tune and Nvidia’s GPU Boost present (namely, huge swings in dynamic power consumption). We feed all relevant currents and voltages into a multi-channel 500 MHz oscilloscope (HAMEG HMO 3054), which can be remote-controlled and is able to retain the test data.

We measure the currents with three calibrated DC current clamp probes (HAMEG HZO50). Two of them, 3.3 and 12 V, take their readings at a custom-made riser card, which can reliably pass PCIe 3.0 signals, and one of them at a specially-modified PCIe power cable. All voltages are measured at the single-rail power supply, which we slightly modified to allow better access.

Our time resolution is now a mere 2 ms, which can measure and log all load transients incurred by AMD’s Power Tune and Nvidia’s GPU Boost. In order to keep the volume of data manageable, we limit the duration of a test run to two minutes.

Test MethodNo contact current measurement at the PCIe slot (Riser card)
No contact current measurement at the external PCIe power cable
Voltage measurement at the PSU
Test Equipment1 x HAMEG HMO 3054, 500 MHz four-channel oscilloscope
3 x HAMEG HZO50 current probe (1 mA - 30 A, 100 kHz, DC)
4 x HAMEG HZ355 (10:1 probe, 500 MHz)
1 x HAMEG HMC 8012 DSO
Test BenchMicrocool Banchetto 101
Power Supply
Corsair AX860i with slightly modified connectors

What Happens Within 100 ms?

A lot! We log the power draw with three probes at a 2 ms interval and pick a representative 100 ms window. Then we plot the resulting 50 data points in a graph.

Looking at the graph, you almost have to feel sorry for the power supply. Power draw through the PCIe power cables jumps from 140 to 352 W within a few milliseconds. You can't expect just any old generic PSU to cope with that. The two test points at the PCIe riser cards do not exhibit such drastic load changes.

We like that neither AMD nor Nvidia max out the PCIe slot connector's output rating, which is 75 W. Those auxiliary power cables bear the brunt of the load. Nor are there drastic load transients on the motherboard connector. All of this helps ensure system stability, benefiting multi-GPU setups in particular.

Now let's take a look at power consumption in real-world workloads.

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Top Comments
  • 16 Hide
    CaptainTom , May 5, 2014 12:05 AM
    I just want to point out that this and most 290X's beat a stock 780 Ti. The fact is both 780 Ti and the 290X are trade blows and belong on the same GPU tier. However only one does cost $150 less and come with 4GB VRAM...
Other Comments
  • 0 Hide
    combine1237 , May 4, 2014 11:36 PM
    For some reason I thought the pcs+ used hynix.
  • 16 Hide
    CaptainTom , May 5, 2014 12:05 AM
    I just want to point out that this and most 290X's beat a stock 780 Ti. The fact is both 780 Ti and the 290X are trade blows and belong on the same GPU tier. However only one does cost $150 less and come with 4GB VRAM...
  • 5 Hide
    Memnarchon , May 5, 2014 12:14 AM
    Quote:
    I just want to point out that this and most 290X's beat a stock 780 Ti. The fact is both 780 Ti and the 290X are trade blows and belong on the same GPU tier. However only one does cost $150 less and come with 4GB VRAM...


    Well, since you are comparing a non reference GPU, you should take also a non-reference GPU to compare.
    Tom's using Gigabyte's 780ti OC which costs the same as the reference card...

    So even the non-reference models are on a different tier as well as their reference...
  • -1 Hide
    bemused_fred , May 5, 2014 2:37 AM
    Any chance of measurements in metric as well as imperial?
  • 4 Hide
    FormatC , May 5, 2014 3:26 AM
    Quote:
    Any chance of measurements in metric as well as imperial?


    Typical translation errors, the original is in metric ;) 
    http://www.tomshardware.de/powercolor-r9-290x-pcs-review,testberichte-241519-3.html4

    I will clearify with Chris, that we use both in the future. Metric is worldwide more common :D 
  • 2 Hide
    dave_trimble , May 5, 2014 5:11 AM
    Surprised the benchmark graph show performance at 1080p. Aren't the 290 series kind of wasted at that resolution? I would love to see the results at 1440p or even 4k. I have a feeling the 780ti might not look quite as good in comparison at higher resolution.
  • 3 Hide
    photonboy , May 5, 2014 6:26 AM
    A stock GTX780Ti is 7% faster at 2560x1440, and 8% faster at 1920x1080 (18 games averaged):
    http://www.techpowerup.com/reviews/EVGA/GTX_780_Ti_SC_ACX_Cooler/26.html

    With such a HUGE difference in prices, quality, and performance on all top-end cards you really have to do your research.

    The R9-290X prices vary from $550 to $780 USD!
  • 0 Hide
    dave_trimble , May 5, 2014 7:11 AM
    Quote:
    A stock GTX780Ti is 7% faster at 2560x1440, and 8% faster at 1920x1080 (18 games averaged):
    http://www.techpowerup.com/reviews/EVGA/GTX_780_Ti_SC_ACX_Cooler/26.html

    With such a HUGE difference in prices, quality, and performance on all top-end cards you really have to do your research.

    The R9-290X prices vary from $550 to $780 USD!


    Thanks for the response! I thought I had seen reviews elsewhere that showed the 290 series really closing the gap, or even surpassing the 780ti at higher resolutions, but perhaps I was remembering wrong. I recently decided to upgrade to a dual-290 setup, but if I had gone with a single card, the 780ti was at or near the top of my list (until the 290x prices came crashing down, that is).

  • 0 Hide
    That_Guy88 , May 5, 2014 8:38 AM
    So is the difference between 290x's almost entirely due to cooling (and some OC)? I have someone who wants to sell me a reference 290x for $350, but I have a gtx 770, so it would seem that I would need to buy an after market cooler as well to make it worth my while. Thoughts?
  • 1 Hide
    vertexx , May 5, 2014 10:05 AM
    Quote:
    So is the difference between 290x's almost entirely due to cooling (and some OC)? I have someone who wants to sell me a reference 290x for $350, but I have a gtx 770, so it would seem that I would need to buy an after market cooler as well to make it worth my while. Thoughts?

    See these articles for after-market cooling options:
    Air cooling:
    http://www.tomshardware.com/reviews/r9-290-accelero-xtreme-290,3671.html

    Liquid Cooling:
    How to:
    http://www.pcper.com/reviews/Graphics-Cards/Using-NZXT-Kraken-G10-Watercool-Radeon-R9-290
    And results:
    http://www.tomshardware.co.uk/radeon-r9-290-and-290x,review-32872.html
  • 4 Hide
    RedJaron , May 5, 2014 10:55 AM
    If nothing else, I'm happy to see Radeon prices returning to normal.
  • 1 Hide
    Laytonoid , May 6, 2014 12:04 PM
    Get the Sapphire R9 290 Vapor-X. This is almost exactly the same thing except that Sapphires card has a LED Sapphire logo that changes color based on heat and looks way cooler. Also, being an owner of the Vapor-X myself, I can tell you that this card has the Hynix Memory. Highly recommend. Also, the temp has never gone over 65C in my small MATX case in a room that is 71F.
  • -1 Hide
    Laytonoid , May 6, 2014 12:04 PM
    Get the Sapphire R9 290 Vapor-X. This is almost exactly the same thing except that Sapphires card has a LED Sapphire logo that changes color based on heat and looks way cooler. Also, being an owner of the Vapor-X myself, I can tell you that this card has the Hynix Memory. Highly recommend. Also, the temp has never gone over 65C in my small MATX case in a room that is 71F.
  • 0 Hide
    Laytonoid , May 6, 2014 12:05 PM
    Sorry. Didn't mean to double post.
  • 1 Hide
    Laytonoid , May 6, 2014 12:06 PM
    Oh also, the Vapor-X card has the same benchmarks as a 290x in Firestrike Extreme, Valley and Heaven. I got it for 460 bucks.
  • 0 Hide
    That_Guy88 , May 6, 2014 1:24 PM
    Quote:
    Get the Sapphire R9 290 Vapor-X. This is almost exactly the same thing except that Sapphires card has a LED Sapphire logo that changes color based on heat and looks way cooler. Also, being an owner of the Vapor-X myself, I can tell you that this card has the Hynix Memory. Highly recommend. Also, the temp has never gone over 65C in my small MATX case in a room that is 71F.


    I was more wondering about the value of getting the 290x for $350. I could buy an after market cooler for $50-75. I'm just not sure if it is a worth while upgrade.
  • 0 Hide
    RedJaron , May 6, 2014 1:40 PM
    These types of cards have the benefit of being factory OC'd and cooled. Generally speaking, if you swap the cooler and personally OC your card, you void the warranty. If that's a big deal for you, then the 3rd-party boards might be to your liking.

    For total upgrade worthwhileness ( is that even a word/term? ) what kind of resolution are you going for? Most of the top-end cards are complete overkill if you're not playing above 1080p. If you're not using 1440p or triple displays, I wouldn't bother going above a GTX 770 / R9 280.
  • 0 Hide
    redgarl , May 6, 2014 2:06 PM
    After buying a pair of those, I can only recommend them. They are quiet as hell and perform incredibly.

    I am questioning Toms review about the temps. Temps on Hardwarecanucks are showing something entirely different giving the PCS+ the best temps of all the 290x cards offered. A wooping 63C... even mines have never reach up 67C...
  • 1 Hide
    redgarl , May 6, 2014 2:08 PM
    Quote:
    I just want to point out that this and most 290X's beat a stock 780 Ti. The fact is both 780 Ti and the 290X are trade blows and belong on the same GPU tier. However only one does cost $150 less and come with 4GB VRAM...


    Not to forget the only viable 4k option right now in Crossfire.
  • 0 Hide
    Laytonoid , May 6, 2014 2:29 PM
    Sapphire aftermarket cards = Hynix memory
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