Overclocking the XO-1
Warnings
By overclocking your OLPC 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 OLPC is passively cooled, physical damage could easily be caused by excess heat.
The procedure detailed below is relatively safe, cpu and memory voltages are not changed, as that appears to require a hardware hack.
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.
| Value | CPU speed | RAM speed |
|---|---|---|
| 3d3 | 333 MHz | 133 MHz |
| 3d5 | 366 MHz | 133 MHz |
| 3d7 | 400 MHz | 133 MHz |
| 3d9 | 433 MHz | 133 MHz |
| 3db | 466 MHz | 133 MHz |
| 3dd | 500 MHz | 133 MHz |
| 3df | 533 MHz | 133 MHz |
| 3e1 | 566 MHz | 133 MHz |
| 4d3 | 333 MHz | 166 MHz |
| 4d5 | 366 MHz | 166 MHz |
| 4d7 | 400 MHz | 166 MHz |
| 4d9 | 433 MHz | 166 MHz |
| 4db | 466 MHz | 166 MHz |
| 4dd | 500 MHz | 166 MHz |
| 4df | 533 MHz | 166 MHz |
| 4e1 | 566 MHz | 166 MHz |
| 5d3 | 333 MHz | 200 MHz |
| 5d5 | 366 MHz | 200 MHz |
| 5d7 | 400 MHz | 200 MHz |
| 5d9 | 433 MHz | 200 MHz |
| 5db | 466 MHz | 200 MHz |
| 5dd | 500 MHz | 200 MHz |
| 5df | 533 MHz | 200 MHz |
| 5e1 | 566 MHz | 200 MHz |
| 653 | 333 MHz | 216 MHz |
| 655 | 366 MHz | 216 MHz |
| 657 | 400 MHz | 216 MHz |
| 659 | 433 MHz | 216 MHz |
| 65b | 466 MHz | 216 MHz |
| 65d | 500 MHz | 216 MHz |
| 65f | 533 MHz | 216 MHz |
| 661 | 566 MHz | 216 MHz |
| 6d3 | 333 MHz | 233 MHz |
| 6d5 | 366 MHz | 233 MHz |
| 6d7 | 400 MHz | 233 MHz |
| 6d9 | 433 MHz | 233 MHz |
| 6db | 466 MHz | 233 MHz |
| 6dd | 500 MHz | 233 MHz |
| 6df | 533 MHz | 233 MHz |
| 6e1 | 566 MHz | 233 MHz |
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 is an exercise left to the reader.
References
These instructions were rewritten from a guide posted on the OLPC News Forum. The original guide can be found here.