Overclocking by default?

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Overclocking by default?

Postby gandro » Tue Apr 17, 2012 2:43 pm

Hi everyone,

I was lucky to get a Raspberry Pi from the first batch and it arrived today. First thing I did was booting the Arch Linux ARM image (from the official page) and so far everything works great. Thanks to the guys that made this possible!

But I've noticed that that in the "/boot/config.txt" there's the entry "arm_freq=800" which seems odd, because the the Raspberry Pi is supposed to run at 700MHz. /proc/cpuinfo also states that the RP is running at nearly 800MHz, which means that the processor is overclocked:

$this->bbcode_second_pass_code('', 'Processor : ARMv6-compatible processor rev 7 (v6l)
BogoMIPS : 795.44
Features : swp half thumb fastmult vfp edsp java tls
CPU implementer : 0x41
CPU architecture: 7
CPU variant : 0x0
CPU part : 0xb76
CPU revision : 7

Hardware : BCM2708
Revision : 0000
Serial : 0000000047939b9a')

Is this supposed to be this way, or is this a bug? I've read here that overclocking voids the warranty. Not sure whether this is true or not, but if it is then overclocking by default would really be a bad idea..

Edit: Okay, the specs for the config.txt file state that only overvolting voids the warranty.
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Re: Overclocking by default?

Postby falker » Tue Apr 17, 2012 3:04 pm

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Re: Overclocking by default?

Postby gandro » Tue Apr 17, 2012 3:24 pm

Good to know, thank you!
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Re: Overclocking by default?

Postby pepedog » Tue Apr 17, 2012 3:29 pm

The reasoning is that the Broadcom guy who built kernel says its safe and reliable, overclocking doesn't damage, overvolt does.
He runs at 1000 MHz regularly. Plus xbmc just built on pi, now to try.
Edit, why would this compile for cortex A6 vfpv2?
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Re: Overclocking by default?

Postby Philoo » Tue Apr 17, 2012 3:56 pm

pepedog, you seem quite close to the guys at the rasperberryPi foundation. Did they run the full QA tests (possibly including the CE, fcc compliancy) at higher frequency.

This whole overclocking deal is quite interesting, but rings bad bells in my ears as 10 some years ago when intel produced pentium and would rate their speed (133, 166 or 200 MHz) depending on results of the production tests. After a few months and a couple production optimizations and cost reductions, there actually were shortages of higher speed processors.
Overclocked processors would show anything from overheat and reset (I'm not aware of any burnouts) to random processing errors.

So my 2 cents contribution would be to adopt a conservative settings (700MHz) and document believed safe overclocking.
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Re: Overclocking by default?

Postby pepedog » Tue Apr 17, 2012 6:30 pm

Well 3 people seem to have objected, next rootfs I will comment it out.
Or maybe we could arm wrestle, if I win it goes up to 900 :twisted:
Wish it was officially posted what is safe.

No, don't know what went on in tests, apart from it passed.
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Re: Overclocking by default?

Postby bob8889 » Tue Apr 17, 2012 7:05 pm

I agree with pepedog that if the Broadcom guy says it's safe then why not take advantage of a 14% performance improvement.
People who don't want to take the limited risk can set it back to 700.
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Re: Overclocking by default?

Postby pepedog » Tue Apr 17, 2012 8:23 pm

Well I don't agree with myself on this matter, but for myself I'm sticking with 800
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Re: Overclocking by default?

Postby bmentink » Tue May 01, 2012 4:56 am

Off topic a bit, but I bring it up because pepedog mentioned it. Can some one point me to a howto compile/install XBMC for the Pi, or was in just installed with pacman? If so, how was it optimized for the Pi ...
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Re: Overclocking by default?

Postby pepedog » Tue May 01, 2012 8:11 am

Not built yet.
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