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News 64-bit Raspberry Pi 3 launches as first Wi-Fi-enabled board

Discussion in 'Article Discussion' started by Gareth Halfacree, 29 Feb 2016.

  1. GiantKiwi

    GiantKiwi New Member

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    And if that were the only use for them, the CPU upgrade is massive overkill as well, so that point is moot.
     
  2. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    Well, now, that's not actually true, is it? The bundled education software is pretty much all designed to be run on the Pi itself, and the majority of it runs in the desktop. Stuff like Scratch, Wolfram Alpha, BlueJ - these all absolutely *chug* on the original 700MHz single-core Pi. They're usable, just about, but frustrating - and especially so if you're running a web browser in the background for reading tutorials or help pages. The Pi 2 and Pi 3 bring more grunt to the table, and that makes everything a lot more responsive - which means fewer frustrated kids clicking a bajillion times and making something break.

    Then there's people doing compiled languages: compilation takes about a tenth the time - or less - on a Pi 3 than on an original Pi. Sure, you can cut it down considerably further by running a cross-compile environment (or qemu or similar) on a desktop, but at that point you might as well just be using the desktop to learn programming and save yourself the £30.
     
  3. Byron C

    Byron C And now a word from our sponsor

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    That was a lot more measured than my initial reaction...
     
  4. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    So, I've been playing with the Pi 3 for a couple of months now, but I've only just got around to sticking it under the thermal camera ('cos I've got a Hobby Tech column due tomorrow.) This is the result:

    [​IMG]

    Yes, that's a chip temperature of 97°C in a 16°C room - a delta-T of a ridiculous 81°C. Without a case. That's at full CPU load but minimal GPU, so if I were really stressing it we'd be seeing worse.

    If you're buying a Pi 3, do not put it in an existing case - especially compact fully-covered slice-style cases like the Pimoroni PiBow - without a heatsink, and even then make sure you're keeping an eye on the temperatures 'cos it's likely you're going to need to make a cut-out so it can breathe. (Incidentally, that's exactly what Pimoroni has done: the new PiBow has a hole over the SoC and you can be a heatsink that pokes up through said hole for an extra quid.)
     
  5. Byron C

    Byron C And now a word from our sponsor

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    :eeek:

    Toasty!!

    Ambient temp in my home office is ~20-23°C - a delta T of 81°C would be very unpleasant indeed in this room. This may be the first Pi where I don't scoff at the idea of getting a heatsink, as I'm very interested in seeing how well this model can overclock.
     
  6. Parge

    Parge the worst Super Moderator

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    Wowza! What is the maximum rated temp for the chip? Does it throttle under load? How long were you running it at 100% for before it hit that temp?

    I've got some permanent thermal interface material - might use that to bond a heatsink of some description to it.
     
  7. Byron C

    Byron C And now a word from our sponsor

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    If the new chip is anything like the BCM2836 or the BCM2835 then there should be temperature throttling built in. Though I don't know the limits off-hand, or the full details on the new BCM2837...
     
  8. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    85°C; it's supposed to throttle at 80°C, but the internal temperature sensor was convinced it was below that even as I was taking the photo; roughly five minutes. In that order.
     
  9. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    Right, so, I'm bepuzzled. I have two Pi 3s. They're both V1.2, but from different batches: one is a pre-production sample with debug header on its arse, the other is a boxed retail RS model. I can make both reach temperatures well in excess of where it should throttle using SysBench. Both show a very different reading when I read them externally than from their internal temperature sensors when under load (though the readings match at idle). I've verified my findings in three ways: a cheap IR thermometer smushed up against the SoC to account for the 8:1 measurement area growth ratio, which reads higher than the internal sensor; a cheap K-type contact probe connected to a multimeter, which reads higher than the internal sensor; and a really chuffin' expensive, fully calibrated Flir thermal camera, which reads higher than the internal sensor (and yes, I do know how to operate it and have correctly set the distance, reflected temperature and thermal emissivity values. I also pointed it at the kettle with a strip of masking tape on the side to make sure it hadn't got busted somehow. It's fine.)

    I also poked the chip with my finger, and it felt unpleasant enough that I'm willing to believe my measurements.

    Then there's this guy, who also has two Pi 3s from different batches. His don't go above 60°C and the external reading is never more than a few degrees away from the internal sensor. As I did, he's used multiple methods to confirm that - including poking the chip, which was 'ow' but not 'argh.'

    Then there's the Foundation, which has been doing its own testing. Their test Pi, running the same benchmark, hits 83°C externally-measured - lower than mine, hotter than Make's - but correctly throttles as a result, dropping to 77°C before climbing back to 83°C to throttle once more.

    So, explanations on a postcard, please.
     
  10. Byron C

    Byron C And now a word from our sponsor

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    Will certainly be interested to find out what's going on here. What tests were you running in order to get these temperatures? When I get chance I'll see what readings I can get out of the internal temp sensor on mine.

    Unfortunately I don't have a calibrated Flir thermal camera; I do have a finger (several, actually), but I don't think it's ever been calibrated. :)

    I think the short answer is: if you're likely to do anything remotely CPU intensive, get a heatsink on it.
     
  11. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    Just give it a slap across the chops with this at the terminal:

    Code:
    sudo apt-get update && sudo apt-get install sysbench -y
    nohup sysbench --num-threads=8 --test=cpu --cpu-max-prime=10000000000 run &
    watch cat /sys/class/thermal/thermal_zone0/temp
    If it reckons it's sub-80, stick yer finger on it and see if you agree.
    Every home should have one!
    I'd say so, aye.
     
  12. wyx087

    wyx087 Homeworld 3 is happening!!

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    Thanks for that benchmark, looks like a great improvement. This means I can make one out of 4 cores to only do GPIO and sort of guarantee timing. (in microsecond, good enough)

    My problem was that setting pins takes a long time, and when the CPU is busy with other logging tasks, it takes even longer! I'm thinking problem lies with RPi original's lack of other cores. I'm not doing anything timing critical.

    That Parallella board looks just the toy I need! Very cheap for a 7 series Zynq! I'm currently debating whether to go with that board or a RPi3....... I'll need the network stack of a fully functioning OS though. So RPi3 will allow me to more stuff quicker. But I feel more confident in VHDL and Zynq allows me to play around with SDSoc stuff. :sigh: I'm spoiled for choices :D
     
  13. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    The Parallella runs Ubuntu, from memory, so you've got your full-fat OS there.
    It's a good time to be alive if you like playing with small, low-power, affordable computing hardware, innit?
     
  14. Byron C

    Byron C And now a word from our sponsor

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    Well, the internal temp sensor read ~82°C in fairly short order after throwing sysbench at it, although I can't confirm the external reading. It seems to hover around 42-44°C at idle.

    This is all in an ambient room temperature of ~25°C.

    Methinks a heatsink is definitely in order.
     
  15. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    Got an explanation for the guy from Make seeing a peak of 60°C - if you feed the Pi 3 an inadequate power supply or a crap USB cable, it throttles down to 600MHz regardless of temperature. The only people I'm seeing saying theirs hits anything less than 70°C unmodified are suffering from that problem - and while the guy from Make hasn't responded to my messages, I'm willing to bet that was the case with his Pis as well.

    Still trying to find people with accurate means of measuring the external temperature of the chip. I can't be the only Pi 3 owner with a thermal camera, surely?!
     
  16. Byron C

    Byron C And now a word from our sponsor

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    Interesting, that would make sense. I'm guessing we no longer get the little rainbow square in the corner to warn of power problems?

    Frankly I'm surprised my Pi3 ran from the 1.8A phone charger I usually use; it had keyboard, mouse, power for a 5" LCD screen, and a USB stick all hanging off the USB ports. I'm assuming it didn't throttle itself anyway since I was reading temps of around 80°C.
     
  17. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    You should do, but at least one person claims they had no rainbow (but did see the power light flash, which is the other warning of low power).
    Yeah, it'd have been closer to 60 if it were running at 600MHz. You can check easily, though:

    Code:
    sudo apt-get update && sudo apt-get install sysbench -y
    nohup sysbench --num-threads=8 --test=cpu --cpu-max-prime=10000000000 run &
    watch '(vcgencmd measure_temp; vcgencmd measure_clock arm)'
    That'll run a CPU stress test while printing the reported temperature and clock speed of the chip. If you're seeing it drop to 600MHz, that's power throttling; thermal throttling should see it drop in increments, not by half.
     
  18. Parge

    Parge the worst Super Moderator

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    I bought a heatsink and a 'Coupe' case with a hole for said heatsink for the new 3.

    Also a Class 10 Sandisk Ultra MicroSD - supposedly has a read speed of 80mbps which I'd imagine makes things a bit more pleasant (assume the pi supports those kinds of speeds)

    EDIT: Gareth, I'm a Twitch streamer - at the moment I encode on my CPU (which is fine) but I'd love to be able to offload my stream to the Pi 3 for encoding and upload - is there any way of doing that? At the moment a lot of people build entire secondary PC's for that, but with the speed of the new Pi 3 I'm thinking it might be possible to use that. It would definitely be something a LOT of streamers would be interested in.
     
    Last edited: 6 Mar 2016
  19. Vault-Tec

    Vault-Tec Green Plastic Watering Can

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    This could finally be the thing that gets me off my ass and makes me build some sort of Android console for emulation.
     
  20. Byron C

    Byron C And now a word from our sponsor

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    There's some work being done with HDMI input over the camera port, but it's in very early stages at the moment and not really ready for anyone other than developers.

    You'd have to get the video in to the Pi somehow; USB2 doesn't have the bandwidth for HD video so you'd have to use some sort of external capture dongle on the Pi... which would have its own encoder built in so you wouldn't actually be using the Pi to encode video, only upload.

    I went round the houses on this one a few times, and unless you can afford a spare PC which can grab uncompressed 1080P then you're better off with a single PC and using things like Intel QuickSync (what I use/used, incidentally), dedicated capture hardware, or pure software encoding.
     

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