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Nvidia's Tegra 4 GPU: Doubling Down On Efficiency

Maximizing Performance Per Millimeter Squared

Nvidia clearly needed to make difficult decisions in order to enable Tegra 4’s GPU in just 10.5 square millimeters of die space—less than Qualcomm’s Adreno 320, ARM’s Mali-T604, or Imagination Technologies’ PowerVR SGX554MP4. Holding off on a unified shader architecture, forgoing features that would have met OpenGL ES 3.0/Direct3D 9_3 minimum specifications, and paring back Tegra 4i’s features show that the company kept its eye on a number of tough targets.

Ultimately, though, we’re not looking at PC-equivalent content on mobile platforms yet. Nvidia’s leadership says the company approached Tegra 4 with rendering efficiency in mind, and the in-house benchmarks we’ve seen tend to back this up. Instead of focusing on frame rates or expensive features, the numbers compare GPU area and power consumption.

Tegra 3Tegra 4Tegra 4/Tegra 3
GLBenchmark 2.5 Frame Rate720p, On-Screen57 FPS60 FPS
Power (mW)2,294 mW1,521 mW
Performance/Watt24.939.41.6x
GLBenchmark 2.5 Frame Rate1080p, Off-Screen12 FPS54 FPS
Power (mW)1,629 mW3,674 mW
Performance/Watt7.414.72x

Source: Nvidia

Here’s one example: in GLBenchmark 2.5’s on-screen 720p test, Tegra 3 must go all-out to achieve 57 FPS, using 2.3 W in the process. Tegra 4 pegs the display’s refresh at 60 Hz. But because it doesn’t get taxed by that workload, it only draws 1.5 W. The result is 1.6x Tegra 3’s performance (in FPS) per watt. Conversely, if you let Tegra 4 run unconstrained by rendering out to an external 1920x1080 display, it’s able to do 4.5x Tegra 3’s frame rate using 2.25x as much power. That neatly works out to 2x the performance per watt.

Granted, those are Nvidia’s internal numbers, and they ultimately only cover one of the SoC’s subsystems. However, we already know from ARM Vs. x86: The Secret Behind Intel Atom's Efficiency that power is the front on which other vendors are most eager to do battle with Nvidia. A Tegra 4 able to deliver better battery life in the next generation of Android-based games would certainly put Qualcomm and Samsung on notice. We’ll have to see how much success Nvidia has convincing Microsoft to allow some of Tegra 4’s more advanced features under Windows RT, though.

  • s3anister
    I'm always amazed with the progress made in strides in this ultra-competitive sector so it's nice to see nvidia finally hit 28mm with Tegra 4. I'm sure some of their performance gains can be attributed to this.
    Reply
  • levin70
    Charlie at semiaccurate is correct. The Tegra 4 is DOA. Almost no one will be using it. Everyone else is already ahead of where the T4 is today, and it hasn't even launched. How many design wins were noted? 1?

    Yeah, says it all.
    Reply
  • Memnarchon
    A Sunday article? :O
    Reply
  • deedee2die4
    Nvidia staying on top, the best of the best!
    Reply
  • blazorthon
    deedee2die4Nvidia staying on top, the best of the best!
    Uhh, no... T4 isn't supposed to be out for like six months, yet it's already not as fast as some of Qualcomm's latest. Nvidia is improving, but as usual, they're staying a little behind in technology.
    Reply
  • aicom
    levin70Charlie at semiaccurate is correct. The Tegra 4 is DOA. Almost no one will be using it. Everyone else is already ahead of where the T4 is today, and it hasn't even launched. How many design wins were noted? 1?Yeah, says it all.Nobody is ahead of Tegra's four Cortex A15 cores. Krait is at less performance than A15 (until the refresh at least). Samsung's got Exynos 5 Octa, but that's not out yet either and T4 will probably still top it in the GPU performance department. Speaking of which, Tegra 4 has the most powerful GPU in floating-point of anyone (including the iPad 4) with 74.8 TFLOPS @ 672 MHz. It only takes a 825 MHz Cortex A15 to match a 1.6 GHz A9, and Tegra 4 is supposed to ship at 1.9 GHz. Unfortunately, TDP does go up in the process.

    You also have to look at where these parts are targeted. Krait is really gunning for phone design wins and they have many. It's a very power efficient chip that found its way into some very nice phones. Tegra 4 is not aimed at that market; Tegra 4i is. Tegra 4 will have a much higher TDP than 4i (and Krait) and will get substantially higher performance as a result.
    Reply
  • tjosborne
    Hey guys, I am considering getting a Asus transformer prime tablet with the tegra 3. Would it be best to wait till this processor ends up in a tablet to get one?
    Reply
  • So at 1.3Gpix/s, Nvidia has just admitted to 10x overdraw...per second? So we're looking at 9~10 frames per second oh high res displays. Lag lives on.
    Reply
  • PreferLinux
    aicomNobody is ahead of Tegra's four Cortex A15 cores. Krait is at less performance than A15 (until the refresh at least). Samsung's got Exynos 5 Octa, but that's not out yet either and T4 will probably still top it in the GPU performance department. Speaking of which, Tegra 4 has the most powerful GPU in floating-point of anyone (including the iPad 4) with 74.8 TFLOPS @ 672 MHz. It only takes a 825 MHz Cortex A15 to match a 1.6 GHz A9, and Tegra 4 is supposed to ship at 1.9 GHz. Unfortunately, TDP does go up in the process.You also have to look at where these parts are targeted. Krait is really gunning for phone design wins and they have many. It's a very power efficient chip that found its way into some very nice phones. Tegra 4 is not aimed at that market; Tegra 4i is. Tegra 4 will have a much higher TDP than 4i (and Krait) and will get substantially higher performance as a result.You mean Gigaflops, not Teraflops.
    Reply
  • blazorthon
    aicomNobody is ahead of Tegra's four Cortex A15 cores. Krait is at less performance than A15 (until the refresh at least). Samsung's got Exynos 5 Octa, but that's not out yet either and T4 will probably still top it in the GPU performance department. Speaking of which, Tegra 4 has the most powerful GPU in floating-point of anyone (including the iPad 4) with 74.8 TFLOPS @ 672 MHz. It only takes a 825 MHz Cortex A15 to match a 1.6 GHz A9, and Tegra 4 is supposed to ship at 1.9 GHz. Unfortunately, TDP does go up in the process.You also have to look at where these parts are targeted. Krait is really gunning for phone design wins and they have many. It's a very power efficient chip that found its way into some very nice phones. Tegra 4 is not aimed at that market; Tegra 4i is. Tegra 4 will have a much higher TDP than 4i (and Krait) and will get substantially higher performance as a result.
    S4 Pro is a faster CPU IIRC. IDK about how the graphics compares and won't comment about it.

    Nvidia, like I said, is getting better, but they're still going to be a little behind. They're making up a lot of ground here, especially with how they're making Tegra 4 and Tegra 4i instead of a single SoC to take both places, but they seem like they'l still have a little room to make up, at least in CPU performance, to be the best. Like I said before (at least in other articles about it), they'll still be near the top either way.
    Reply