ProDigit
Posts: 374
Joined: Tue Aug 30, 2011 1:24 am

Pi 3B+ Overclocking

Fri Aug 09, 2019 6:22 am

I've found conflicting data on the internet on the Pi 3B+ on overclocking; most between 6 months to 1 year old posts.

I wondered if current batches of 3B+ better than previous?

I put a heat sink on any major chip on the Pi 3B+.
Just a heat sink.
The CPU got the largest one (about 1/2"). 2 more smaller sinks on the top of the board, and one sink on the bottom.

My current OC settings are:

Code: Select all

arm_freq=1500
sdram_freq=525
gpu_freq=400
over_voltage=1
And it runs fine.
Running a CPU benchmark utility, with 4 cores at 100% gets the CPU running at 80C after about 5 minutes, and doesn't really go much beyond that.

The CPU ran fine to 1500Mhz with zero overclock voltage adjustment (voltage read ~ 1,24??V). I just added over_voltage to '1' for stability, measuring now at 1.2688V.
It seems to run stable.

Are these values normal?

I don't really do a lot of heavy CPU taxing. Mostly just coding, so my CPU runs stock at 60C, and at 1500Mhz at 64C at nearly idle (<10% load with browser open).

The 1500Mhz makes it a bit more snappy, as the Pi 3B+ feels a little sluggish.

dominic03
Posts: 91
Joined: Fri Dec 21, 2018 1:50 am

Re: Pi 3B+ Overclocking

Fri Aug 09, 2019 11:25 am

I use the following:

Code: Select all

arm_freq=1525
core_freq=550
gpu_freq=720
h264_freq=700
sdram_freq=575
over_voltage=2
temp_soft_limit=70
Note that temp_soft_limit will change the time from where it throttles down to 1200mHZ from 1525mHZ to 70 degrees Celsius. The default throttle temp is 60 degrees.
Last edited by dominic03 on Sun Aug 11, 2019 11:51 pm, edited 3 times in total.
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ProDigit
Posts: 374
Joined: Tue Aug 30, 2011 1:24 am

Re: Pi 3B+ Overclocking

Sat Aug 10, 2019 4:58 am

From the terminal, my setting seems to throttle down to 1,2Ghz after like 82-83C.
It stays mostly at 1,5Ghz during the entire time under load (since it usually stays between 75-80C tops, and if I tilt it, and let some air flow in, it cools down by a few degrees, and doesn't pass ~77C even under a stress test).

Are these settings safe for any Pi? Or is yours actively cooled?

pik33
Posts: 187
Joined: Thu Sep 10, 2015 4:26 pm

Re: Pi 3B+ Overclocking

Sat Aug 10, 2019 6:30 am

I have active cooled (3cm fan @3.3v) RPi3 set at 1400/560/560 +force_turbo=1. It can run at 1500 but it is unstable: in (rare) occasion it hangs up, so I left it at 1400. What helps a lot is the core and RAM speed, it gives the RPi3 a lot of additional power even when the CPU is not overclocked

ProDigit
Posts: 374
Joined: Tue Aug 30, 2011 1:24 am

Re: Pi 3B+ Overclocking

Sat Aug 10, 2019 7:04 am

Strange. I have bought my Pi3B+ recently, and it runs fine at 1,5Ghz, though it's mostly idling around 600Mhz.
I did notice glitches when bumping the RAM speed to 550, so I backed it off a bit to 525, and it runs stable, passively cooled.
I yet have to try the core frequency.

Current settings:

Code: Select all

arm_freq_min=366 
>> Down to 350Mhz this setting doesn't really affect GUI sluggishness.

arm_freq=1500 
>> (By far, this gave the biggest boost in snappyness factor to me. OS responds great!)

sdram_freq=525 
>> My RAM had artifacts at 550Mhz
core_freq=525
>> Not sure what values work out well here.
core_freq_min=225
>> 150 made system noticeably sluggish, 
>> 200Mhz setting is nearly perceivably slower from stock 250)

gpu_freq=550 (<-600Mhz worked but errored on glxgears)
gpu_freq_min=200 (<-150 may have been too slow. GPU reacts sluggish)
over_voltage_min=-3 
>> (lower voltage means cooler idle, -4 gave stability issues. 
>> -3 gave stability issues at 300Mhz arm_freq_min, probably because of low voltage, and frequent upthrottling, but seems to work fine at 350Mhz)
..Still editing some values..

I also didn't adjust the over_voltage setting, as it runs fine at 1,5Ghz, and with it's setting at '1', the CPU would begin to throttle at ~79C.
With stock voltage (over_voltage=0), the CPU's max temperatures hover between 76 and 77C (no throttling).

User avatar
Imperf3kt
Posts: 3383
Joined: Tue Jun 20, 2017 12:16 am
Location: Australia

Re: Pi 3B+ Overclocking

Sun Aug 11, 2019 10:09 pm

ProDigit wrote:
Fri Aug 09, 2019 6:22 am
And it runs fine.
Running a CPU benchmark utility, with 4 cores at 100% gets the CPU running at 80C after about 5 minutes, and doesn't really go much beyond that.
probably hitting the thermal throttle. Type vcgencmd get_throttled in a terminal. Anything other than 0x0 is unwanted.
ProDigit wrote:
Fri Aug 09, 2019 6:22 am
I don't really do a lot of heavy CPU taxing. Mostly just coding, so my CPU runs stock at 60C, and at 1500Mhz at 64C at nearly idle (<10% load with browser open).
at idle, the Pi drops to 600MHz, it isn't running at 1500MHz
Last edited by Imperf3kt on Mon Aug 12, 2019 11:24 pm, edited 1 time in total.
55:55:44:44:4C
52:4C:52:42:41

ProDigit
Posts: 374
Joined: Tue Aug 30, 2011 1:24 am

Re: Pi 3B+ Overclocking

Mon Aug 12, 2019 11:14 pm

with the settings above, the Pi idles around 350Mhz, and runs even cooler (55-57C)

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