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How much can I overclock?

Posted: Sun Jun 09, 2013 12:25 pm
by therpiguy
I want to overclock my pi but I am not sure about the power stuff.

Here are my power supply specs.

Input: AC100-240v
0.2A Max 50-60Hz

Output:DC5.0V
1000mA

Thx

Re: How much can I overclock?

Posted: Sun Jun 09, 2013 2:07 pm
by klricks
The power supply has not much to do with overclocking. The main fuse F3 will only reliably allow about 750mA into the board. The question is how much overclocking can you do without sustaining corruption to the filesystem on the SD card? I tried OC max and got corruption in a matter of minutes and had to re-image my SD card. I don't OC at all now.

Re: How much can I overclock?

Posted: Sun Jun 09, 2013 2:16 pm
by pluggy
As with over clocking anything, suck it and see on your particular setup. There is no "ready reckoner".

Re: How much can I overclock?

Posted: Sun Jun 09, 2013 3:29 pm
by W. H. Heydt
The easiest way to set up overclocking is to do it through raspi-config. Then you can look at /boot/config.txt to see what the actual setting are, and read documentation to see how they work.

The highest that raspi-config will set to is 1GHz, so you can reasonably take that as a limit for how high you can go (unless you take extreme measures like active cooling...which in some experiments in years past--not, so far as I know, on a Pi--has been done with liquid Nitrogen).

Re: How much can I overclock?

Posted: Mon Jun 10, 2013 12:10 am
by miker00lz
I've got my raspi running at 1.0 GHz CPU, 500 MHz SDRAM clock, overvolt is set to 6. I'm using force_turbo as well. It's totally stable, I have QEMU running on it right now. Windows Server 2003 guest OS installed, and it's been running perfectly with a full-time 100% CPU load for 2 days. The CPU isn't even that warm. I might try to see if I can jack it up even more later. It's handling it well so far.

Re: How much can I overclock?

Posted: Mon Jun 10, 2013 7:11 am
by shawn-pi-noob
miker00lz wrote:I've got my raspi running at 1.0 GHz CPU, 500 MHz SDRAM clock, overvolt is set to 6. I'm using force_turbo as well. It's totally stable, I have QEMU running on it right now. Windows Server 2003 guest OS installed, and it's been running perfectly with a full-time 100% CPU load for 2 days. The CPU isn't even that warm. I might try to see if I can jack it up even more later. It's handling it well so far.
Wait, how did u get windows server 2003 guest os on it. Please explain it simple because im only 14.

Re: How much can I overclock?

Posted: Mon Jun 10, 2013 11:48 am
by Liber
klricks wrote:The power supply has not much to do with overclocking. The main fuse F3 will only reliably allow about 750mA into the board. The question is how much overclocking can you do without sustaining corruption to the filesystem on the SD card? I tried OC max and got corruption in a matter of minutes and had to re-image my SD card. I don't OC at all now.
I read many threads related to overclocking and there was power supply described as key for successful overclocking due to ability of deliver enough voltage. A power supply with more than 1.200mA was usually recommended. If I am mistaken, please correct me. ;)

Re: How much can I overclock?

Posted: Mon Jun 10, 2013 12:19 pm
by dom
Liber wrote:
klricks wrote:The power supply has not much to do with overclocking. The main fuse F3 will only reliably allow about 750mA into the board. The question is how much overclocking can you do without sustaining corruption to the filesystem on the SD card? I tried OC max and got corruption in a matter of minutes and had to re-image my SD card. I don't OC at all now.
I read many threads related to overclocking and there was power supply described as key for successful overclocking due to ability of deliver enough voltage. A power supply with more than 1.200mA was usually recommended. If I am mistaken, please correct me. ;)
You are quite correct. I have about 10 Pi's lying around. All support arm_freq=1000 (with overvolt). All support core_freq=500. All support sdram_freq=500 (and some sdram_freq=600).
*But* only with a good power supply and good lead. A (genuine) iPhone charger is okay.
If I power from Panasonic TV's USB socket, or router's USB socket, I can run at stock speeds, but I get crashes when I overclock.

From my experience power supply is the most important factor when overclocking.

Re: How much can I overclock?

Posted: Mon Jun 10, 2013 12:27 pm
by Heater
miker00lz,
I've got my raspi running at 1.0 GHz CPU, 500 MHz SDRAM clock, overvolt is set to 6. I'm using force_turbo as well. It's totally stable, I have QEMU running on it right now. Windows Server 2003 guest OS installed, and it's been running perfectly with a full-time 100% CPU load for 2 days.
Interesting. Has Windows 2003 finished booting up yet:)

Do you have ant instructions for getting that monstrosity working?

Apart from geek appeal is there any particular reason to want to do this?

Re: How much can I overclock?

Posted: Mon Jun 10, 2013 1:25 pm
by lewmur
Liber wrote:
klricks wrote:The power supply has not much to do with overclocking. The main fuse F3 will only reliably allow about 750mA into the board. The question is how much overclocking can you do without sustaining corruption to the filesystem on the SD card? I tried OC max and got corruption in a matter of minutes and had to re-image my SD card. I don't OC at all now.
I read many threads related to overclocking and there was power supply described as key for successful overclocking due to ability of deliver enough voltage. A power supply with more than 1.200mA was usually recommended. If I am mistaken, please correct me. ;)
You are not wrong. Though the Pi won't draw more than 750ma, a PS rated a 1000ma will often still have too much of a voltage drop when drawing 750ma. PS's are normally rated by their "charging" ability and a voltage drop during "high charging" isn't critical. But it is critical when supplying a Pi. Particularly when OCing. I know you can buy a charger for an HP TP on ebay for under $5, rated for 2A. Why buy anything less?