Overclocking

[a9971256]

I noticed that when I have no cooling system attached and the system crashes, the LAN ic is still blinking the LEDs, even when I ping it. Is that normal or is it a defect

[Gert van Loo]

I

I noticed that when I have no cooling system attached and the system crashes, the LAN ic is still blinking the LEDs, even when I ping it. Is that normal or is it a defect

The LEDs are driven directly by the LAN chip and are independent of any CPU activity.

[XBMCantgetenough]

The ram used to have a hard cap at 600mhz which with early models Samsung hit very easily and Hynix were lucky to hit 500 with no overvolting so it may be worth pointing out which ram you have.

I assume this was 1/4 of 2400 or something and that this limit no longer applies?

600MHz is still the limit. I do need to investigate if increasing the 2.4GHz PLL limit, or using a smaller divisor is possible.

So the limit of sdram=600? I've set 710 on my config.txt, I guess my Pi was ignoring this value. Is there a command to verify the sdram?

[a9971256]

I think my pi might have been ignoring 1400 MHz. It was staying down locked to 700 MHz. What art the proper ways to overclocking without raspi config? Do I have to change Linux settings to allow turbo to work dynamically. Also, in my pi application, my pi will stay on for 10 minutes and will be shut down, so cooling might not be a problem here. Powered by lead acid battery, psu shouldn't be an issue. LmM3940 gives 4.9 volts under pi 1 ghz usage with filter capacitor

[a9971256]

Yesterday, I forced turbo and ran a power-heavy application (GCC and netbeans) and it ran stably at 47 deg (2 deg above AZ outside temp). I was watching the temp and turned off forced cooling. It went up to 60 deg in 1.5 min. Is that a good enough cooling system to run stably pi at 1.2 ghz?

[MaxK1]

If it works - yes. If not - no.

[MaxK1]

Seriously, I don't think many RPi owners have been able to push their boards to 1.2GHz or beyond. I have 5,
3 of which have been pushed to 1.1+ (I thought 1180 was doable on one of them, but it did not last.)
So, I keep all 3 at 1.12 and they stay running, even though I could go to 1.15, maybe a bit more, on at least two of them.
I have only (briefly) used passive cooling (big chunk of aluminum) and it did reduce the temp by several degrees.
Who needs random failures and instability?

[shalo]

So the limit of sdram=600? I've set 710 on my config.txt, I guess my Pi was ignoring this value. Is there a command to verify the sdram?

I don't really understand how anyone is verifying anything. How did you test it to arrive at a figure of 710? If ~600 works, anything over 600 should work just the same. Seems odd that you would find a 710 figure.

I'm not even sure it is definitively a 600mhz limit since I'm not sure dom ever stated where it is derived from. He can't know everything off the top of his head can he?

The first step with overclocking though is usually a quick test. Back in the day with 900mhz cpu and 250mhz core/gpu I set about finding the RAM limit of my boards. standard memcpy produced results that were fairly linear for ram.
400mhz = 344.62
450mhz = 352.96
500mhz = 364.46
550mhz = 372.02
600mhz = 374.75
I don't have any of the 600+ saved but it was this that suggested to me that the limit might be a little below 600mhz. Testing wasn't very extensive however since someone else had already suggestd the limit in this very thread and it was clear from other benchmarks that there isn't much to be gained from ram speed compared to core/cpu anyway.

I think my pi might have been ignoring 1400 MHz. It was staying down locked to 700 MHz. What art the proper ways to overclocking without raspi config? Do I have to change Linux settings to allow turbo to work dynamically. Also, in my pi application, my pi will stay on for 10 minutes and will be shut down, so cooling might not be a problem here. Powered by lead acid battery, psu shouldn't be an issue. LmM3940 gives 4.9 volts under pi 1 ghz usage with filter capacitor

I don't understand how this is even really possible. Surely when you are overclocking the very first thing you do is run a simple benchmark to see how your new settings have changed things. With cpus it's usually something very simple like SuperPI 1M. You'll very quickly see some sort of quantitative result or a fail. Then you do a broader set of benchmarks that stress a little more, then finally you do an actual stress test to make sure it's stable. If it passes this final stability test, you might decide to push it some more. If it fails you look at your results and see if you are happy to give it more power or back off on the overclock which is usually a more considered decision back in the desktop world where heat can be the major factor.


File modified date on my testing is 26/08/2012. Am I correct in thinking that "current_limit_override=0x5A000020" wasn't in the wild until mid September 2012 and this might have been a factor in some strange q3 results I saw where I was getting fails that I would not normally have expected? It would stand to reason that a mild overclock that I expect to succeed that fails instantly might fail just the same when adding more voltage since adding more voltage could never help under those circumstances?

[XBMCantgetenough]

So the limit of sdram=600? I've set 710 on my config.txt, I guess my Pi was ignoring this value. Is there a command to verify the sdram?

I don't really understand how anyone is verifying anything. How did you test it to arrive at a figure of 710? If ~600 works, anything over 600 should work just the same. Seems odd that you would find a 710 figure.

The 710 came from increasing incremental steps. I didn't pluck 710 out of knowhere. If I go to about 720 It seems to crash more often (openelec) so I thought 710 must be valid, and its working at the speed. But that is what I thought about my core speed. I can set the core @700 and it boots but the Pi ignores it. But strangely enough If I set it at 720 then it doesn't even load. So logic tells me that it must have accepted thee 700 value. But running vcgencmd I can confirm I can't get past 600. And at 560 I get a increase in fps (openelec) as apposed to setting core@700. So thats why I would like to know if there is a way to measure the ram. And plus it would be helpful if this limit for the varaibles is written in http://elinux.org/RPiconfig

[a9971256]

What I am trying to find out is when you use raspi config, does it change any settings within Linux that controls the dynamic clocking?

[asb]

What I am trying to find out is when you use raspi config, does it change any settings within Linux that controls the dynamic clocking?

When you set overclock with raspi-config, it adds a script to /etc/init.d that runs at boot and switches the CPU governor to the "ondemand" governor (and tries to detect if the shift key is held down to skip this, in case you overclock too far).

[portets]

600MHz is still the limit.

Are you sure this is still the RAM limit? I used to be able to put in any number higher than 600 just fine. Now if I put in 700 or higher the Pi only makes it halfway through the boot process before spitting errors and freezing.

[XBMCantgetenough]

Are you sure this is still the RAM limit? I used to be able to put in any number higher than 600 just fine. Now if I put in 700 or higher the Pi only makes it halfway through the boot process before spitting errors and freezing.

Have you tried overvolting sdram, mine works but starts to reboot on heavy load, once every 10 mins after intial 30 minutes of on. Also use this which helps disable_pvt=1. I've gotten 710 working but like i said its not stable for long

over_voltage_sdram=8
disable_pvt=1

[a9971256]

I don't know what just happened. I rebooted my pi as just an occational reboot and it ain't overclocking no more. I haven't changed any settings so something's going awry

[a9971256]

why does the pi have such a wimpy processor? The gpu is overrated because many times the processor ain't fast enough for the gpu. my iphone 3gs has a better processor compared to pi but has a worse gpu (i believe it has an equivalent to the VideoCore II). is there a board with the TI A15? A15 Keystone processor running at 5.6GHz seems overkill.

[portets]

why does the pi have such a wimpy processor? The gpu is overrated because many times the processor ain't fast enough for the gpu. my iphone 3gs has a better processor compared to pi but has a worse gpu (i believe it has an equivalent to the VideoCore II). is there a board with the TI A15? A15 Keystone processor running at 5.6GHz seems overkill.

The Pi is actually faster than the 3GS when in turbo mode. The 3GS is capable of 1200 DMIPS, and the Pi is capable of 1250 DMIPS when overclocked to 1000MHz ARM. That number is even higher when core_freq is doubled in turbo mode. The Pi also has double the RAM than the 3GS. And as you mentioned, the Pi has a much faster GPU.

The difference is that iOS is heavily optimized on the 3GS, but raspbian is based on a desktop OS.

The Pi will be much smoother and quicker when Wayland/Weston replace Xorg.

[a9971256]

Is there something I have to do in occidentalis to overclocking past 1000 arm? Everything else seems that it is ocing

[fernandovg]

dom, I'm using this settings for a while:
hdmi_force_hotplug=1
hdmi_mode=32
arm_freq=1050
core_freq=500
isp_freq=255
sdram_freq=450
over_voltage=6
disable_overscan=0
gpu_mem=155
start_file=start_x.elf
fixup_file=fixup_x.dat

and its stable (gpu_mem is higher because I was getting problems with subtitles. There were showing as blocks and not chars)

Can I add?
gpu_freq=500
over_voltage_sdram=1

thanks!

[XBMCantgetenough]

dom, I'm using this settings for a while:
hdmi_force_hotplug=1
hdmi_mode=32
arm_freq=1050
core_freq=500
isp_freq=255
sdram_freq=450
over_voltage=6
disable_overscan=0
gpu_mem=155
start_file=start_x.elf
fixup_file=fixup_x.dat

and its stable (gpu_mem is higher because I was getting problems with subtitles. There were showing as blocks and not chars)

Can I add?
gpu_freq=500
over_voltage_sdram=1

thanks!

Do you mean sdram_freq=500 with over_voltage_sdram=1? since why would you want to increase volts to sdram if its stable @ 450? and by changing the volts to sdram I'm assuming that your intentions was to increase sdram

If thats what you mean then yes, but increase the sdram_freq=500 without increasing volts and if it doesn't stick then increase the volts.

If you actually meant gpu_freq=500 that is very high and I don't think it would work and also why would you want to increase it so much, it already runs 1080p at default 250

and lastly change isp_freq=255 to isp_freq=250 because the isp needs to be a multiple of core.

Hope that helps

[fernandovg]

Using this since yesterday and its stable
Im using raspbmc with 4 more other programs.

Code: Select all

hdmi_force_hotplug=1
hdmi_mode=32
arm_freq=1050
core_freq=500
gpu_freq=500
sdram_freq=500
over_voltage=6
disable_overscan=0
gpu_mem=155
start_file=start_x.elf
fixup_file=fixup_x.dat

If I want cpu to 1150 what do I need to change?
Thanks

[bryanandaimee]

You'll probably need

force_turbo=1
and over_voltage=8

[MaxK1]

arm_freq=1150

really should be in there somewhere....

[fernandovg]

i know...

but what other values should I change?
thanks

[PieterJ]

Found out the hard way how important the stable power supply is for overclocking.

Now running OpenArena benchmark stable at

• 1160 ARM
• 650 Core
• 400 GPU
• 600 SDRAM
• overvoltage=8
• overvoltage_sdram=6

I had a lot of SD Card corruption issues when clocking GPU over 350MHz (with high arm, core, sdram). With another USB cable I can go past 400MHz GPU easily.

• "long usb cable" at USB2.0 port => 4.45V under load
• "long usb cable" at USB3.0 port => 4.51V under load
• "short usb cable" at USB3.0 port => 4.71V under load

[Dilligaf]

ALL those voltages are too low, try finding a better power supply.