overclocking


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by Raspberry wino » Tue May 08, 2012 3:22 pm
I'm not going to do it but I still want to know HOW.Several mentions of cooling but how do you change the speed? Is it a config setting somewhere or changing the crystal... or what?
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by abishur » Tue May 08, 2012 3:40 pm
basically you need to make a file in /boot named config.txt inside it put

arm_freq=

then the speed you want to overclock the pi.

There are actually a lot of settings you can make in config.txt and some of them can void your warranty (such as overvoltage) so play with caution!  This thread gives a very comprehensive list of the options in config.txt
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by remondo » Tue May 08, 2012 3:47 pm
I'll be testing the Raspberry Pi's resistance to a blender.
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by abishur » Tue May 08, 2012 3:52 pm
remondo said:


I'll be testing the Raspberry Pi's resistance to a blender.



You know I keep seeing that mentioned and I know that a google search will probably answer the question for me, but are we talking about a real physical blender thereby destroying the pi or are we talking about a software stress test?
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by milhouse » Sun May 13, 2012 10:18 pm
abishur wrote:You know I keep seeing that mentioned and I know that a google search will probably answer the question for me, but are we talking about a real physical blender thereby destroying the pi or are we talking about a software stress test?


The former.

http://www.youtube.com/watch?v=qg1ckCkm8YI

Hmm... doesn't seem possible to embed YouTube videos in the new forum. :(
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by abishur » Mon May 14, 2012 2:03 pm
milhouse wrote:
abishur wrote:You know I keep seeing that mentioned and I know that a google search will probably answer the question for me, but are we talking about a real physical blender thereby destroying the pi or are we talking about a software stress test?


The former.

http://www.youtube.com/watch?v=qg1ckCkm8YI

Hmm... doesn't seem possible to embed YouTube videos in the new forum. :(


Hmm... well I must confess I've never understood the fun in the destruction of a product that is, at the time, limited and in high demand, it is your money.
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by blc » Mon May 14, 2012 5:48 pm
remondo wrote:I'll be testing the Raspberry Pi's resistance to a blender.


I really hope you're not serious. At least not until there is a plentiful supply and everyone can get one within a week or so.
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by ssbtoday » Mon May 14, 2012 10:59 pm
abishur wrote:basically you need to make a file in /boot named config.txt inside it put

arm_freq=

then the speed you want to overclock the pi.

There are actually a lot of settings you can make in config.txt and some of them can void your warranty (such as overvoltage) so play with caution!  This thread gives a very comprehensive list of the options in config.txt



Haha... Inplying that the Raspberry Pi has a warranty. XD
:)
I'd love to see the results from this...
Also, is it possible to overclock the GPU clock too? I might want a couple more Megaflops teehee. :)
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by jamesh » Tue May 15, 2012 7:54 am
Yes, the Raspi has a warranty. However it is voided if you overclock (and if it is overclocked a OTP is set so we WILL KNOW!). That said, you shoudl be able to get 900-1Ghz reliably, but chip life will be reduced. You shouldn't need extra cooling.

It is possible to overclock the GPU, but it's generally not very successful and needs to be done in the blob, so cannot be done by users. It runs at 250MHz and has twin CPU's, each a 16 way vector core, so quite a lot of power there anyway.
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by milhouse » Tue May 15, 2012 8:43 am
jamesh wrote:Yes, the Raspi has a warranty. However it is voided if you overclock (and if it is overclocked a OTP is set so we WILL KNOW!). That said, you shoudl be able to get 900-1Ghz reliably, but chip life will be reduced. You shouldn't need extra cooling.

It is possible to overclock the GPU, but it's generally not very successful and needs to be done in the blob, so cannot be done by users. It runs at 250MHz and has twin CPU's, each a 16 way vector core, so quite a lot of power there anyway.


Minor correction but the warranty is only voided when the user overvolts - it's not voided if the user is simply overclocking (increasing clock frequency without changing voltage). The OTP is only blown (voiding the warranty) if any of the SoC voltages are increased above default - changing clock frequency is entirely safe and will not void the warranty.
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by dom » Tue May 15, 2012 9:00 am
jamesh wrote:It is possible to overclock the GPU, but it's generally not very successful and needs to be done in the blob, so cannot be done by users. It runs at 250MHz and has twin CPU's, each a 16 way vector core, so quite a lot of power there anyway.


You can overclock GPU with gpu_freq= as described in config.txt thread.
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by milhouse » Tue May 15, 2012 9:07 am
dom wrote:
jamesh wrote:You can overclock GPU with gpu_freq= as described in config.txt thread.


I've had no success with that "global" GPU setting - the Pi would fail to display a GUI but I have been able to overclock the GPU modules individually using core_freq and h264_freq, leaving the rest of the GPU at default although even overclocking these two modules by only a small amount (<10%) introduced visible glitches/artifacts when playing back media (OpenELEC).
Last edited by milhouse on Tue May 15, 2012 9:29 am, edited 1 time in total.
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by jamesh » Tue May 15, 2012 9:13 am
dom wrote:
jamesh wrote:It is possible to overclock the GPU, but it's generally not very successful and needs to be done in the blob, so cannot be done by users. It runs at 250MHz and has twin CPU's, each a 16 way vector core, so quite a lot of power there anyway.


You can overclock GPU with gpu_freq= as described in config.txt thread.


Ah, thanks Dom, didn't know that. Is the post above right - it's only overvolting that void the warranty?
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by rey » Tue May 15, 2012 9:16 am
I can hit 925 comfortably. I'm going to try overvolting and attempt to break the 1Ghz barrier tonight.
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by shirro » Tue May 15, 2012 9:34 am
I thought my Pi was running fairly reliably at 800Mhz but I had occasional weird stuff happening under load. Overclocking the sdram made it more unreliable. It might run for days with a light load but is useless running benchmarks. Luck of the draw I guess. Back to 700Mhz for me and hopefully the next one does better.

Running gtkperf against xvfb was 4 times slower on my Pi at 800Mhz than a 1Ghz Cortex A8 which might go some way to explaining why X is slow. No amount of overclock is going to make much of a dent in that I think.
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by rey » Tue May 15, 2012 10:18 am
Yeah, 925 is my limit without overvolting. It'll boot at 950 but it's incredibly unstable.
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by dom » Tue May 15, 2012 11:39 am
jamesh wrote:Ah, thanks Dom, didn't know that. Is the post above right - it's only overvolting that void the warranty?


Yes. The belief is that the worst that can happen from overclocking is your Pi will crash. It shouldn't have any affect on lifespan (no more than running it in a slightly warmer room).
Overvoltage does reduce lifespan slightly. I think our predictions are that it will still run continuously for 10+ years *with* overvoltaging. However I think our predictions have a high margin of errror...
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by Nr90 » Tue May 15, 2012 3:02 pm
Dom you mention having run yours slightly overvolted at 1ghz.
Have you tried overvolting further and raising the clock speed even further?

If so, what was the highest point you ran it at?
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