Claud has posted an interesting guide here on how to downgrade firmware only on Sony PS3 Slim console. Not directly, but internally. This is very useful if you have a PS3 Slim console with newer PS3 firmware than the 3.41 which you want to Jailbreak.
Although, i am not sure with Claud’s statement that the PS3 firmware was installed in the internal hard drive instead of the system’s memory of PS3 Slim. If you have anything to say about this, please drop a comment. I really would like to know your thoughts since i have no experience swapping hard drives in my PS3 slim console myself. You can read Claud’s guide here:
If you have a PS3 SLIM Edition, then you need to open the PS3 and take out the internal hd:
1. Connect it to a PC
2. Delete the partition on it or format it
3. Put back the hd inside the ps3
4. Have a usb flash ready with firmware 3.41 under [ROOT] PS3Update folder structure
5. Install the 3.41 firmware
6. Works only with the new PS3 SLIM Editions, FAT does not store the firmware on the internal hd
UPDATE: Ryan has posted this, so i guess the guide above is useless?
The firmware is stored on the NAND or motherboard. So when u put in a new or formatted hard drive it will read the firmware previously istalled
UPDATE 2: euss has posted more on this with a bit more explanation.
The only way to correctly downgrade any PS3 with current knowledge is a hardware Infectus modification. This way you can dump your NAND and restore the (personalised and encrypted) NAND.
The personalisations of your console is based on:
[Console Serial Number] + [Main circuit board ID] + [BD Drive] + [WLAN board (MAC address)]
They are bound to each other in SCEI IDServer
Source: PS3 service mode Jig set-up manual.pdf (page 22)
Therefore you cannot download a NAND dump of someone else and flash it in your system.
UPDATE 3: A little bit more from euss to prove that downgrading on PS3 consoles are very impossible.
The Bootloader for firmware is in NAND/Flash for ALL PS3 models.
“The PS3 has 256 megabytes of flash memory to store firmware, using two NAND 128MB Samsung flash chips. The installed firmware data is interleaved between the two flash chips for speed. To prevent errors, Error Correcting Code (ECC) Checksum is added/used on the data in the PS3 flash chips. In newer PS3, a single 16MB Spansion flash chip is used. ”
After removing your harddisk, the bootloader in NAND will report that it already has a newer version and thus will disallow installation of older versions.