Overclocking wiki page rewritten

[suprjami]

What started out as a formatting tidy resulted in me documenting most of what I know about the Raspberry Pi and overclocking it.

https://github.com/RetroPie/RetroPie-Setup/wiki/Overclocking

Enjoy!

[BuZz]

@suprjami nice job! Thanks :-)

[cyperghost]

@suprjami Nice one!

[Brunnis]

@suprjami Awesome job! This is a great reference. I have found two issues, though:

You mention several times that force_turbo = 1 voids the warranty. However, the formula for voiding the warranty is:

(force_turbo || current_limit_override || temp_limit>85) && over_voltage>0

See https://www.raspberrypi.org/forums/viewtopic.php?p=176865#p176865 It's an old post, but I haven't seen anything that suggests this was changed.

The second issue I found is that according to https://www.raspberrypi.org/documentation/configuration/config-txt.md the gpu_freq setting actually sets core_freq and all other GPU related frequencies to the same value. The wiki page makes it seem as if core_freq and gpu_freq are unrelated. Or maybe that page on raspberrypi.org is outdated? Could be, since all overclocking related info in it seems to be RPi 1 related.

[suprjami]

@Brunnis hey thanks for the references! i've been meaning to test those, but have had some other stuff going on and haven't been near the computer much

i also find a lot of overclocking info for the Pi is either outdated or conflicting or just wrong. like the Pi 3 and Zero come with core and GPU at different speeds, so maybe one doesn't set the other there? i haven't tried yet

as i understand it, if the two core and gpu are set to different things, an unexpected frequency may result which can be calculated with: https://github.com/superjamie/snippets/blob/master/pioc.py

i figured it was best to err on the side of caution and explicitly set both. tbh i don't think there are super-huge gains to be had by clocking them differently, at least not for N64/Dreamcast/PSP purposes

i will test more and update the wiki page when i get back into it

[Shakz]

Excellent work....very very thorough. Love it!