

There is a more detailed list on the PS3 developer wiki, look at the downgradable min praxis column that corresponds to your model number. In general all fat systems are downgradable, while most slims are, and no super slims are. Because 3.55 was the last exploitable system firmware version, all installation methods involve downgrading to 3.55 through flashing the firmware memory chip on the motherboard. To install custom firmware your PS3 needs to be downgradable to firmware version 3.55. I personally installed custom firmware primarily to be able to view system temperatures, so that I could mod my CECHA01 to run cooler, and to be able to play backups of my games. There are many more uses, those are just a few. Viewing system temperatures, and manually controlling fan speed.


Update: I have written another post going into more detail on custom firmware installation using a Teensy on a CECH-2001A PS3 slim. This post describes my experiences during PS3 custom firmware installation on my fat CECHA01 console, and my brother's slim CECH-2101A console. Installing custom firmware onto my PS3 was one of my goals I mentioned in my project introduction post.
