Overclocking the XO-1
Warnings
By overclocking the XO-1 laptop you are running the hardware outside the design specifications. Overclocking your CPU and/or RAM may cause stability problems, data errors, and possibly hardware damage. As the XO-1 is passively cooled, physical damage could easily be caused by excess heat.
On the other hand, the processor will skip cycles if it is too warm, and will become slower as a result of heat.
The procedure detailed below is relatively safe, because CPU and memory voltages are not changed, as that would require electrical changes.
How to
First, get to an Open Firmware Ok prompt.
Type the following commands:
ok 4c000014 ok rdmsr ok u. ok u.
After this, two hex values will be displayed. Write down the second one that is displayed. For example, this may display 7de009e.
Now you must choose how much to over (or under) clock your CPU and RAM speeds.
The table below lists the value you will need to overclock, and what speeds this value over (or under) clocks the CPU and RAM to.
| XO-1 Overclock Settings in MHz; default is 433/166 (4d9) |
|||||
| CPU | Bus Speed | ||||
| 133 | 166 | 200 | 216 | 233 | |
| 333 | 3d3 | 4d3 | 5d3 | 653 | 6d3 |
| 366 | 3d5 | 4d5 | 5d5 | 655 | 6d5 |
| 400 | 3d7 | 4d7 | 5d7 | 657 | 6d7 |
| 433 | 3d9 | 4d9 | 5d9 | 659 | 6d9 |
| 466 | 3db | 4db | 5db | 65b | 6db |
| 500 | 3dd | 4dd | 5dd | 65d | 6dd |
| 533 | 3df | 4df | 5df | 65f | 6df |
| 566 | 3e1 | 4e1 | 5e1 | 661 | 6e1 |
Now it's time to do the overclocking itself.
Type the hex value you wrote down in the previous step into the prompt and press Enter. Then type the overclocking value you chose into the prompt and press Enter.
Next, type the following:
ok 4c000014 ok wrmsr
If it worked, it will appear that nothing has happened. If you have pushed the settings too far your system may have frozen or spontaneously rebooted, just power off and choose a more conservative setting and try again.
Your XO-1 is now overclocked! Keep in mind that this overclock is only persistent until the system is rebooted. Making it permanent was an exercise left to the reader. See Custom_bootloader#Sample_Uber_Bootscript.
References
These instructions were rewritten from a guide posted on the OLPC News Forum. The original guide can be found here.
See also Custom_bootloader#overclock.