Nvidia GeForce GTX 970 And 980 Review: Maximum Maxwell

A New Power Consumption Test Setup

Nvidia's newest architecture presents us with a whole new set of challenges for measuring power consumption. If the maximum of all four possible rails are to be measured exactly (to find out Maxwell’s power consumption reduction secrets), then a total of eight analog oscilloscope channels are needed. This is because voltage and current need to be recorded concurrently at each rail in real-time. If the voltages are measured and then used later, the result may be inaccurate. So, how did we solve this problem?

We enlisted the help of HAMEG (Rohde & Schwarz) to search for a solution with us. In the end, we had to use two oscilloscopes in parallel (a master-slave triggered setup), allowing us to accurately measure and record a total of eight voltages or currents at the same time with a temporal resolution down to the microsecond.

The measurement intervals need to be adjusted depending on the application in question, of course, in order to avoid drowning in massive amounts of data. For instance, when we generate the one-minute graphs for graphics card power consumption with a temporal resolution of 1 ms, we have the oscilloscope average the microsecond measurements for us first.

We use a riser card on the PCIe slot (PEG) to measure power consumption directly on the motherboard for the 3.3 and 12 V rails. The riser card was built specifically for this purpose.

In addition, we separately measure the voltage and current at each of the two individual PCIe power connectors.

Test MethodologyNo-contact current measurement at all rails
Direct voltage measurement
IR real-time monitoring
Test Equipment2 x HAMEG HMO3054, 500 MHz Four-Channel Oscilloscope with Data Logger
4 x HAMEG HZO50 Current Probe
4 x HAMEG HZ355 (10:1 Probe, 500 MHz)
1 x HAMEG HMC8012 DSO with Data Logger
1 x Optris PI450 80 Hz Infrared Camera + PI Connect
Test SystemIntel Core i7-5960X, 4.2 GHz
16 GB G.Skill Ripjaws DDR4-2666 (4 x 4 GB)
MSI X99 Gaming 7
2 x Transcend SSD370 (System, Applications + Data, Storage)
be quiet! Dark Power Pro 1200 W
Microcool Banchetto 101

Nvidia’s GPU Boost Accelerates Maxwell

Everything makes sense in theory, but we still want to know how Maxwell achieves better efficiency at this magnitude. Kepler already adjusted the GPU’s voltage quickly and exactly depending on its load and temperature, and AMD’s PowerTune did the same thing as well. It turns out that Maxwell refines the formula further. With its shaders fully utilized, the new architecture's advantage over Kepler practically vanishes. So, Maxwell depends on its superior ability to adjust to changing loads, and, consequently, it’s able to tailor the power consumption even better to the needs of the application in question. The more variance there is, the better Maxwell fares.

To illustrate, let’s take a look at how Maxwell behaves in the space of just 1 ms. Its power consumption jumps up and down repeatedly within this time frame, hitting a minimum of 100 W and a maximum of 290 W. Even though the average power consumption is only 176 W, the GPU draws almost 300 W when it's necessary. Above that, the GPU slows down.

Now, how do the PSU’s important 12 V rail's current and voltage behave under these conditions? We add them up for this purpose.

The PSU doesn’t supply a constant 12 V supply voltage. Spikes that empty the secondary capacitors and the slower power supply that tries to fill them back up again cause voltage fluctuations that the graphics card's five phases must take care of. All of these interactions make our measurements more complicated than a log of averages would suggest.

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  • Vivecss
    Wow.......
  • lancear15
    I was waiting for Tom's review to make my final decision, the 980 is definitely going into my current 5960x build! I cant wait.
  • HKILLER
    so how long before you do a round up?i mean this time i've seen some pretty crazy looking cards (Zotac's Extreme AMP! edition looks crazy and the Inno3D too)and EVGA has shown off ACX 2.0 which they claim to be the most efficient GPU air cooler in the world...so many to choose from also EVGA FTW has been nicely overclocked i've seen it performing almost on par with 980
  • realibrad
    byt he way... Last page 2nd sentence after the graph of Avg game performance.

    I was hoping for more performance but the efficiency is quite nice. They just put pressure on the top end and gave us a price reduction, instead of overall performance gains.
  • balister
    Very nice, but I still want to see what the power consumption along with what might be possible with the drop to 20nm (since this is still 28nm).

    Likely, we're going to see a Maxwell Titan equivalent come in the next year or so as these are a x04 much like Kepler with the 670/80s were and we're still going to be waiting to see what the x10 will be with the Maxwell architecture.
  • MANOFKRYPTONAK
    Why didn't you include an overclocking comparison? Why didn't you include the 780, but included the 770? Doesn't make much sense...
  • vertexx
    970 is the real story until the 980ti comes out - what a value proposition with the 970!

    Good stuff here - but you guys were a bit slow on this one. Tom's Hardware is the first site I visit every morning. But with the delay of this article, I've been all over the net this morning on other sites that got their stuff out sooner.
  • daveys93
    Will there be a follow-up article about overclocking these cards? Other sites are showing results that both of the new cards are capable of 1500+ MHz on air (aftermarket coolers and even a few with stock coolers), which is a massive overclock. Looks like NVIDIA left the door open for some decent voltage increases, but many results have been in the 1450-1500 MHz range at stock voltage. I am a big fan of the thoroughness of Tom's articles so I am very interested in seeing overclocking results and analysis from this site.
  • nikolajj
    I need this...
  • tobalaz
    I want a 970, wow!
    That's some flat out insane price / performance ratio right there!
  • cleeve
    671978 said:
    Why didn't you include an overclocking comparison? Why didn't you include the 780, but included the 770? Doesn't make much sense...


    Same answer to both... no time.

    We literally got the 970 for testing yesterday. The 980, we got the day before. We barely got the article out by this morning.

    For those of you who want more info, we'll be spending more time with the GeForce GTX 980 and 970 in the weeks to come, don't you worry. ;)
  • BigMack70
    Since we know this is only the mid-size Maxwell chip (just like GK104 vs GK110), shouldn't this article title be "Medium Maxwell"?

    I'm waiting for the real Maximum Maxwell myself. Unimpressed with these xxx04 launches from Nvidia.
  • EnkiduW
    Wonder what dual 970's would look like, the price is not that bad...
  • MANOFKRYPTONAK
    Why didn't you include an overclocking comparison? Why didn't you include the 780, but included the 770? Doesn't make much sense...
  • vertexx
    1765452 said:
    Wonder what dual 970's would look like, the price is not that bad...


    http://www.techpowerup.com/reviews/NVIDIA/GeForce_GTX_970_SLI/

    Depending on resolution, dual 970's are roughly equal to the 295x2 at only 2/3's the price.
  • Novuake
    Performance aside, which OBVIOUSLY is stellar for current price/performance consideration.

    The features that Nvidia has been rolling out constantly has been quite impressive, while many of them do not appeal to me at all, the sheer amount and in most cases quality of them is insane.

    Well done Nvidia. Let's see what AMD responds with, my next main gaming machine purchase as of now are 2 x Nvidia GTX970.

    EDIT : Im sure that its a good upgrade to my 2 x HD7950s :D
  • Novuake
    21257 said:
    671978 said:
    Why didn't you include an overclocking comparison? Why didn't you include the 780, but included the 770? Doesn't make much sense...
    Same answer to both... no time. We literally got the 970 for testing yesterday. The 980, we got the day before. We barely got the article out by this morning. For those of you who want more info, we'll be spending more time with the GeForce GTX 980 and 970 in the weeks to come, don't you worry. ;)


    Thank you! That answered a question I had in a previous GTX980/970 tease on the live news feed.

    Do you guys have this problem often with Nvidia? You always seem to have fewer Nvidia board partner variaty and slower review releases on Nvidia GPUs.
    More so than other websites.
  • vertexx
    554342 said:
    21257 said:
    671978 said:
    Why didn't you include an overclocking comparison? Why didn't you include the 780, but included the 770? Doesn't make much sense...
    Same answer to both... no time. We literally got the 970 for testing yesterday. The 980, we got the day before. We barely got the article out by this morning. For those of you who want more info, we'll be spending more time with the GeForce GTX 980 and 970 in the weeks to come, don't you worry. ;)
    Thank you! That answered a question I had in a previous GTX980/970 tease on the live news feed. Do you guys have this problem often with Nvidia? You always seem to have fewer Nvidia board partner variaty and slower review releases on Nvidia GPUs. More so than other websites.


    My bets are that no NVidia GPUs on the best GPU's for the $$ for the past several months earned Tom's a slight delay in the delivery of these GPUs. :ouch:
  • Novuake
    1293856 said:
    My bets are that no NVidia GPUs on the best GPU's for the $$ for the past several months earned Tom's a slight delay in the delivery of these GPUs. :ouch:


    Nah, doubt Nvidia is that petty.

    More publicity is exactly that, more publicity.

    Tom's has been around a long time and is trusted by A LOT of people.
    Doubt Nvidia would compromise the user base.
  • Nossy
    Nvidia and Intel are so way ahead of AMD...
  • oxiide
    671978 said:
    Why didn't you include an overclocking comparison? Why didn't you include the 780, but included the 770? Doesn't make much sense...


    Agreed that overclocking would have been interesting to see. But would including the 780 have added anything to this? The GTX 970 is already faster than an R9 290X.

    The 770, at least, allows us to see the direct improvement from one x70 card to its replacement. Especially when they're approximately the same price.
  • Novuake
    Just read some of the benches again, dear lord those number at that price. Can not get over it...

    Now lets see if they can satisfy my overclocking needs.

    Hurry up with that portion Cleeve!
    When can we expect it?
  • legokill101
    and just to add on while I am very excited about the better price/performance and performance per watt I would honestly say that while the increased efficiency is great, most enthusiast run a single gpu in a full atx case with ample airflow and because of that, I feel like features and price/performance, tend to dictate most purchases of gpu, not performance for watt (which isn't to say its not a good thing)
  • Novuake
    118801 said:
    Nvidia and Intel are so way ahead of AMD...


    Don't count AMD out of the GPU world yet, they still need to respond with their release.

    As for AMD CPUs, I have given up in the enthusiast market, but still have high hopes for low cost and low power APUs bringing affordable gaming to mobile devices.