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Full HDFull HDPosted Oct 21, 2012 21:28 UTC (Sun) by dlang (✭ supporter ✭, #313)In reply to: Full HD by arekm Parent article: The Boxee Box: too free to live?
> I don't want to overclock pi.
Overclocking beyond the manufacturers spec is a problem.
But the manufacturers have said that as long as the temp doesn't get too high, these clock rates are safe.
At that point, what's the difference between "overclocking" and the "turbo mode" that the latest Intel chips have where they can shut down some cores to run other cores at a higher clock rate and still keep within the thermal limits?
XBian mildly overclocks the pi in this safe, manufacturer approved way, and is significantly snappier than raspbmc.
That said, even Raspbmc is not significantly less responsive than my DVR when navigating around. I haven't tried doing so while a video is playing.
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Full HD Posted Oct 21, 2012 21:35 UTC (Sun) by dlang (✭ supporter ✭, #313) [Link]
putting it another way, if the timeing had been slightly different and the pi folks had released the pi as a 1GHz system with thermal limiting that would drop it's speed down to 700MHz if it got too hot instead of listing it as a 700MHz system that could be overclocked up to 1GHz as long as you didn't let it get too hot would you still feel the same way?
what's the difference between the two?
Full HD Posted Oct 22, 2012 18:34 UTC (Mon) by cmccabe (guest, #60281) [Link]
> what's the difference between the two?
Overclocking is by definition not supported by the manufacturer.
I freely admit that I have not done any research on it, but just based on your comment, it sounds like the pi folks were having thermal dissipation issues at the higher frequencies. You can feel free to second-guess the engineers, but only at the risk of significant problems-- like melting the device, starting a fire, etc.
Full HD Posted Oct 22, 2012 18:48 UTC (Mon) by dlang (✭ supporter ✭, #313) [Link]
> Overclocking is by definition not supported by the manufacturer.
This is supported by the manufacturer
http://www.raspberrypi.org/archives/2008
Introducing turbo mode: up to 50% more performance for free
Since launch, we’ve supported overclocking and overvolting your Raspberry Pi by editing config.txt. Overvolting provided more overclocking headroom, but voided your warranty because we were concerned it would decrease the lifetime of the SoC; we set a sticky bit inside BCM2835 to allow us to spot boards which have been overvolted.
We’ve been doing a lot of work to understand the impact of voltage and temperature on lifetime, and are now able to offer a “turbo mode”, which dynamically enables overclock and overvolt under the control of a cpufreq driver, without affecting your warranty. We are happy that the combination of only applying turbo when busy, and limiting turbo when the BCM2835′s internal temperature reaches 85°C, means there will be no measurable reduction in the lifetime of your Raspberry Pi.
You can now choose from one of five overclock presets in raspi-config, the highest of which runs the ARM at 1GHz. The level of stable overclock you can achieve will depend on your specific Pi and on the quality of your power supply; we suggest that Quake 3 is a good stress test for checking if a particular level is completely stable. If you choose too high an overclock, your Pi may fail to boot, in which case holding down the shift key during boot up will disable the overclock for that boot, allowing you to select a lower level.
What does this mean? Comparing the new image with 1GHz turbo enabled, against the previous image at 700MHz, nbench reports 52% faster on integer, 64% faster on floating point and 55% faster on memory.
Full HD Posted Oct 23, 2012 22:51 UTC (Tue) by Lennie (subscriber, #49641) [Link]
Overclocking the Raspberry Pi is not only supported by the manufacturer, I believe they even have a driver which keeps an eye on the builtin temp. sensor.
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