Unlocking the 8th SPE
You should be familiar with the fact that the playstation 3 has 7 enabled SPEs (one is dedicated to isolation) and 1 disabled SPE to increase the yield effectiveness during manufacturing.
Upon startup, the syscon firmware will read the Syscon's EEPROM value located at 0x48C30 (You can read/write to that offset through the Update Manager) and will set the cell config ring accordingly. (it gets sent by Syscon through the SPI bus)
That value is initially set to 0x06 on all consumer consoles which means 7 SPEs are actually enabled (The count starts at SPE0). Incrementing it will unlock the extra SPE.
That means you can possibly unlock an extra SPE for your Linux or other uses (depending whether your 8th SPE is dead or not)
This procedure has been successfully tested on one of my playstation 3 units (CECH-2500), you may however get unexpected result should your 8th SPE happen to be defective)
Alternatively you could hook the SPI bus and modify the config ring on the fly but that requires additional hardware.