The RasPi overclocks very easily; it’s just a matter of adding some text to a file called “config.txt” on the SD Card.

If you want to modify (or create) this file while you’re running OpenELEC, you just have to run these quick steps:

  • SSH in to the device
  • Mount the SD Card as Read-Write 
    mount -o remount,rw /flash
  • Edit the file 
    vi /flash/config.txt
  • Save
  • Reboot

With XBMC-Based installs, overclocking the CPU makes the most difference, and is the easiest to achieve.

Without over-volting (which voids the warranty), the sweet spot seems to be 850Mhz, which is added to config.txt as

arm_freq=850

If you want to dive much deeper on the quest for an optimal overclock, check these guys out.