Power Consumption

There's a lot of uncertainty around whether or not Kepler is suitable for ultra low power operation, especially given that we've only seen it in relatively high TDP (compared to tablets/smartphones) PCs. NVIDIA hoped to put those concerns to rest with a quick GLBenchmark 2.7 demo at Siggraph. The demo pitted an iPad 4 against a Logan development platform, with Logan's Kepler GPU clocked low enough to equal the performance of the iPad 4. The low clock speed does put Kepler at an advantage as it can run at a lower voltage as well, so the comparison is definitely one you'd expect NVIDIA to win. 

Unlike Tegra 3, Logan includes a single voltage rail that feeds just the GPU. NVIDIA instrumented this voltage rail and measured power consumption while running the offscreen 1080p T-Rex HD test in GLB2.7. Isolating GPU power alone, NVIDIA measured around 900mW for Logan's Kepler implementation running at iPad 4 performance levels (potentially as little as 1/5 of Logan's peak performance). NVIDIA also attempted to find and isolate the GPU power rail going into Apple's A6X (using a similar approach to what we documented here), and came up with an average GPU power value of around 2.6W. 

I won't focus too much on the GPU power comparison as I don't know what else (if anything) Apple hangs off of its GPU power rail, but the most important takeaway here is that Kepler seems capable of scaling down to below 1W. In reality NVIDIA wouldn't ship Logan with a < 1W Kepler implementation, so we'll likely see higher performance (and power consumption) in shipping devices. If these numbers are believable, you could see roughly 2x the performance of an iPad 4 in a Logan based smartphone, and 4 - 5x the performance of an iPad 4 in a Logan tablet - in as little as 12 months from now if NVIDIA can ship this thing on time.

If NVIDIA's A6X power comparison is truly apples-to-apples, then it would be a huge testament to the power efficiency of NVIDIA's mobile Kepler architecture. Given the recent announcement of NVIDIA's willingness to license Kepler IP to any company who wants it, this demo seems very well planned. 

NVIDIA did some work to make Kepler suitable for low power, but it's my understanding that the underlying architecture isn't vastly different from what we have in notebooks and desktops today. Mobile Kepler retains all of the graphics features as its bigger counterparts, although I'm guessing things like FP64 CUDA cores are gone.

Final Words

For the past couple of years we've been talking about a point in the future when it'll be possible to start playing console class games (Xbox 360/PS3) on mobile devices. We're almost there. The move to Kepler with Logan is a big deal for NVIDIA. It finally modernizes NVIDIA's ultra mobile GPU, bringing graphics API partity to everything from smartphones to high-end desktop PCs. This is a huge step for game developers looking to target multiple platforms. It's also a big deal for mobile OS vendors and device makers looking to capitalize on gaming as a way of encouraging future smartphone and tablet upgrades. As smartphone and tablet upgrade cycles slow down, pushing high-end gaming to customers will become a more attractive option for device makers.

Logan is expected to ship in the first half of 2014. With early silicon back now, I think 10 - 12 months from now is a reasonable estimate. There is the unavoidable fact that we haven't even seen Tegra 4 devices on the market yet and NVIDIA is already talking about Logan. Everything I've heard points to Tegra 4 being on the schedule for a bunch of device wins, but delays on NVIDIA's part forced it to be designed out. Other than drumming up IP licensing business, I wonder if that's another reason why we're seeing a very public demo of Logan now - to show the health of early silicon. There's also a concern about process node. Logan will likely ship at 28nm next year, just before the transition to 20nm. If NVIDIA is late with Logan, we could have another Tegra 3 situation where NVIDIA is shipping on an older process technology.

Regardless of process tech however, Kepler's power story in ultra mobile seems great. I really didn't believe the GLBenchmark data when I first saw it. I showed it to Ryan Smith, our Senior GPU Editor, and even he didn't believe it. If NVIDIA is indeed able to get iPad 4 levels of graphics performance at less than 1W (and presumably much more performance in the 2.5 - 5W range) it looks like Kepler will do extremely well in mobile.

Whatever NVIDIA's reasons for showing off Logan now, the result is something that I'm very excited about. A mobile SoC with NVIDIA's latest GPU architecture is exactly what we've been waiting for. 

Comments Locked


View All Comments

  • fteoath64 - Thursday, July 25, 2013 - link

    "Do Intel and PowerVR have similar tricks up their sleeve?". Not Intel but PVR likely with Rouge. The key competitor here is Qualcomm with their Adreno 330 powerhouse. That has time to evolve to better efficiency and tuning. But competition on the mobile side is heating up with this announcement and potentially Nvidia's shilf to quickly make this part available. Bigger tablets and UltraLight notebooks can benefit from it rather than settle with Intel's junk iGP.
    The disappointment of the market is no real Tegra4 and Tegra4i products in the market after such delays while Qualcomm churns out model after model of products for OEMs.
  • ocre - Thursday, July 25, 2013 - link

    huh? I really dont know what you people are talking about. Tegra 4s closest competition is the snapdragon 800 which is almost nonexistent in the market. Tegra 4 is beating the SD800 in almost every way. Including design wins!!!

    "While some will argue that Nvidia's design wins are on the weak side, they have more announced design wins than their competitor, Qualcomm with the Snapdragon 800"

    so while you guys might always have negative views towards nvidia, its not nearly as bad as you guys try to make it out to be
  • phoenix_rizzen - Thursday, December 19, 2013 - link

    4 months later, and there's dozens of phones and tablets out with Snapdragon S800 SoCs inside; while there are ... how many with Tegra4?

    Doesn't matter how many "design wins" you have on paper if none of them ever reach the marketplace.
  • michael2k - Thursday, July 25, 2013 - link

    Yes. PowerVR has had similar performance available to licensees last January. Their first chips are expected to be out this year.
  • lmcd - Wednesday, July 24, 2013 - link

    We won't necessarily see the PowerVR implementations to beat this but the fact is that they exist and likely could beat this.

    PowerVR needs reference implementations like all hell.

    Qualcomm will beat this.

    Doesn't 1-2 GCN cores do well against this, too?

    Finally, Intel is already close, and will probably get this performance soon after T5 comes out, with lower power thanks to process advantage.
  • TheJian - Monday, August 5, 2013 - link

    If we won't see a powervr to "necessarily" beat this why discuss it? They don't exist until...umm...They EXIST. :) If I can't BUY it, it doesn't exist :)

    I have a dream in my head of a 50000 gpu core soc that is less than .1w and 10000Tflops gpu power. Do I now have the fastest core on the planet? No, it doesn't EXIST until you can BUY it. Your first sentence really made me laugh. The fact is they don't exist. I'll give you powervr chips that beat this don't exist YET, but that's still just a MAYBE they will...ONE DAY. They'll face bankruptcy if nobody goes for mips tech. They clearly don't make enough from gpus on every apple device to survive the next few gens. TI exited due to not buying icera (or any modem), and Imagination may exit due to mips meaning nothing (could be wrong, we'll see - deving for mips is a tough sell I'd think vs arm/x86). I suspect they'll be bought or die in under 5yrs. They have a market cap of 1B if memory serves and make about 30mil/yr (only 2012, less previously, we'll see for 2013). Good luck keeping up with everyone else making 12x or far MORE than that in the same business. You're dead or bought. Apple could by them for the equivalent of a song (not sure why they haven't) but maybe they're making their own to dump them eventually. They bought PA Semi for the inhouse cpu. Do they have a gpu coming? Otherwise why not purchase IMG.L? They are already in everything you make. Odd, whatever.

    The process advantage is disappearing quickly for Intel. Shortly Intel will have to out CHIP the competition, not out fab them. It's a new ballgame from here on out for Intel and the competition's profits blows Intel's away (IE Samsung making almost Intel's yearly profits in a Q). You can't outspend the competition on fabs when they make 3.5x what you do per year and can spend it all on FAB R&D until you go broke. Intel raised 6B in bonds to fund a buyback. It's a sign on weakness IMHO. They will have to cut dividends soon also (last I checked they can't fund them for more than a few years and even less with dropping profits). Again a sign of weakness.

    Let me know when powervr (in something other than Apple products) beats a T4, let alone T5. I can't see a product yet :) Anything COULD beat NV. But until something DOES in a PRODUCT who cares? I'll need to see shipping product doing it first. Just like people ranting on lack of T4 wins (well duh, it just came out), I don't see S800 announcements right and left either. Why? It's NOT out either (not shipping in enough volume for massive announcements anyway, not yet). T4 just started shipping in July to ODM's.

    I can predict everything will beat a T4 in 5 yrs...LOL. But none of it is shipping NOW. I can buy a toshiba tablet with T4 now (and HP also), though I wouldn't want the toshiba until quality is better. They appear to have design problems with their tablet. But it's shipping now. Qcom will beat this, but WHEN? And how do you know? S800 won't do it vs. T5 (possibly T4 but we don't know in what or if at all yet). Have you seen benchmarks for the next rev past S800? You are special. You work for Qcom or something and have a T5 in your hands? I'll reserve anything regarding AMD for when they actually SHIP a soc.

    Also note Intel has hit 14nm snags recently and is already delaying chips. I agree with your PowerVR needs something for reference out now though ;) Where is this stuff? Are they that far away from shipping something? No xmas for them then, nor S800 if it doesn't get out the door in volume soon. We see T4 announcements from Toshiba, HP (both have T4's for sale), Asus, etc so they will be in xmas stuff for sure. How many S800 devices will make it for xmas? Are they shipping to ODM's yet? I know xperia Z is supposedly coming Sept so it has to be shipping but if anyone has some links to verify that...Then again when they ship devices with 3 different chips they can claim shipping but not really ship your desired chip for months. Exynos 5420 is ramping in Aug this month, but I guess we'll have to wait for Note3 to see T628 MP6 perf. They are claiming it's 2x faster than 5410 PowerVR544MP3. But I'll wait for benchmarks of a T628 before I believe this and battery life to go with that benchmark. How long before it is in a product? Note3 is expected Sept, but it has a long list of supposed chips, so not sure which has the S800 or 5420 or when these come specifically (or if I even have the correct chips, I saw a claim of S600 for one model - who knows at this point). I wish companies would just ship ONE soc per product or name them something different like note3.1 for s800, note 3.2 for 5420 etc etc. Something to differentiate better for customers who don't read every review on the planet. Would the REAL note3 please stand up...LOL. Granted its really about the included modem for specific regions but it's still confusing for a lot of people.

    Intel is moving to their own soc gpus. I'll believe they beat people when I see it in anything gpu :) NV had samples of 20nm socs ages ago, so Intel will need 14nm to do any damage here and broadwell is slipping to 2015. When we will see a 14nm soc if they are having problems? All socs will be 20nm next year, so Intel's 22nm will be facing these (T5 etc) not far after silvermont/valleyview/baytrail release (tablet by xmas, phone next year?). All have sped up 14nm plans, so they won't be too far behind a DELAYED intel 14nm process especially samsung swimming in billions to dump into their fab tech. T6 is supposed to be 16nm finfet early 2015, so not much of a process advantage for Intel at 14nm then and T6 has maxwell in it. Intel better have a great gpu and this won't be a basic arm port for cpu either it is in house DENVER :)

    So 20nm risk production started 2013 Q1, and 16nm risk starts by end of year.
    "Chang indicated that TSMC already moved its 20nm process to risk production in the first quarter of 2013. As for 16nm FinFET, the node will be ready for risk production by the year-end, Chang said."

    So depending on who T6 comes from it's either 16nm (tsmc, it's at least this) or 14nm (sammy?)? Either way Intel faces stiff competition from here out. The fab party is over. Time to make some unbeatable chips or pay the price. You won't outFAB the competition any more. Intel is about to release 22nm tablets/phones and everyone else is about to do 20nm shortly after that. Not sure how that's a real victory. I don't see one at 14nm either. We may actually see Intel get beaten to 10nm if samsung keeps pounding out 7.9B+ in profits per Q (Q1 was 7.9B, 8.3B i think for Q2). This kind of profit can kill Intel's fab lead quickly. Unless they seriously boost profits samsung has 10nm in the bag and that's assuming Intel wins to 14nm which has yet to be proven and is showing problems or broadwell wouldn't be delayed right? Will apple be fabbing for people shortly? They certainly have the cash to build 3-4 fabs today easily and laugh in 3yrs. I'm surprised it hasn't already happened (though they did buy one, why not start some new ones while you're rich?). Well rumor is they bought UMC, but it's probably true. I'd be doing that and building 3 450mm fabs for the future (what's that 20bil for 3 of them? Even at 25-30bil who cares, apple has ~130). Buy IMG.L and start pumping out gpus in one fab, socs in another and memory in a 3rd for all your devices in 3yrs. Samsung makes as much as they do on a device because 60+% of a phone/tablet comes from IN HOUSE.

    As far as I can see this xmas for tablets is owned by S800/T4. Xmas Phones are owned by S600 I think, with maybe enough volume for S800 to make it into some things. T4i is Q1 and will miss xmas, and I don't think 5420 will make it into anything volume wise for xmas as it's just ramping this month.

    T5 will be out before July 2014 on 20nm (so will a 20nm S800 etc). Intel won't be seeing 14nm until 2015 in volume if they crack 2014 at all. I don't call that SOON after T5. Unless you want to say VERY soon after Intel puts out a 14nm soc it will face T6 etc.
  • phoenix_rizzen - Thursday, December 19, 2013 - link

    Here it is, Christmas time, and your predictions are a little off. There are many S800 SoCs in phones, many S600 SoCs in phones, nearly all the good tablets have S800 SoCs, and no Tegra4 to be seen.

    If you can't even predict the next 4 months (July-Dec), why should we listen to your predictions for the next 3 years? :)

    Tegra4 is a flop. Tegra4i is an admission by nVidia that Cortex-A15 can't cut it in phones. And Tegra5 won't be much better (if we even see it in anything by this time next year).
  • Zoolookuk - Sunday, July 28, 2013 - link

    I don't know why people are picking on your comment - faster than A6? I'd hope so, given A6 is form 2012, and this is arriving in 2014. The question is whether it'll be faster than A8, not something from 18 months ago.
  • karasaj - Wednesday, July 24, 2013 - link

    Wow. Even if we account for a new iPad delivering 2x the performance of the last one (unlikely?) Keller is still ahead, potentially in both power and performance. This is crazy!
  • michael2k - Wednesday, July 24, 2013 - link

    Except it will be first among equals. PowerVR 6 is designed to scale up to 1TF, and realistically ship in 200GF to 600GF configurations, making the Logan nothing special.

Log in

Don't have an account? Sign up now