Raspberry Pi Overclocking Benchmarks

Over-clocking a Raspberry Pi?

The Raspberry Pi is an amazing device for $35. I have been tinkering with mine for a few weeks. Recently, the Raspberry Pi group offered directions for over-clocking a Raspberry Pi from its stock CPU frequency of 700 MHz to a “turbo” mode of 1000 MHz. Even better, they have guaranteed that using the “turbo” mode will not void your warranty or damage the Raspberry Pi.

The question I had was – what would the impact be of this overclocking? Therefore, I decided to test the CPU under a number of frequencies from the stock setting of 700 MHz through the “turbo” mode of 1000 MHz. I used the nbench Linux tool to benchmark my Raspberry Pi’s CPU. I changed the CPU frequency via the raspi-config command-line utility.

The results

The following table shows the CPU frequency of my Raspberry Pi and the “integer index” and “floating-point index” calculated by nbench. Higher values are better.

**CPU (MHz)****Integer index****Floating-point index**
70010.7523.474
80013.0244.244
90014.4754.653
95014.5754.501
100016.2375.475
As the table shows, the difference from the stock speed of 700 MHz to 1000 MHz is substantial. This chart shows the steps visually. [![Raspberry Pi Over-clocking Results](https://i1.wp.com/www.evilsoapbox.com/content/images/2013/01/1.png?resize=444%2C319)](http://www.evilsoapbox.com/?attachment_id=1598) What is of special interest to me are the actual performance gains over stock, over the previous level, and the performance per dollar of acquisition costs. ### Performance improvements over stock
**CPU (MHz)****Int improvement (%)****FP improvement (%)**
700100100
800121122
900135134
950136130
1000151158
### Performance improvements over previous speed
**CPU (MHz)****Int improvement (%)****FP improvement (%)**
700100100
800121122
900111110
95010197
1000111122
### Performance index per dollar This table breaks down the performance per dollar of the Raspberry Pi’s cost.
**CPU (MHz)****Cost per Int ($)****Cost per FP ($)**
7003.2610.07
8002.698.25
9002.427.52
9502.407.78
10002.166.39

Conclusions

These benchmarks allow me to draw a few key conclusions.

First, my benchmark results are close (but not identical to) the results from the Raspberry Pi foundation. Therefore, some variability likely explains different results. I used a stock install so I am not sure what they did (or did not do) to achieve higher benchmarks.

Second, the “turbo” mode makes a huge difference! My Raspberry Pi is getting 151% integer performance and 158% floating-point performance over stock. Those are some astounding numbers for a software tweak that is vendor-supported (and endorsed!)

Third, If you do not want to take a risk (some SD card corruption has been reported with the 1000 MHz setting) than using 900 MHz offers the nearly the same performance as the 950 MHz setting. This slower speed may offer more “safety” with a little impact.

Testing notes

To run these tests I disabled wpa_supplicant and transmission-daemon which consistently negatively impacted the nbench results about 3.4%.