QA Flag Downgrade from 3.55
 

How far back can you downgrade from 3.55 with the QA Downgrade method, is it as far back as your ps3 can go or just to 3.15?
Having not been using a PS3 back then, I am only guessing 3.15 is the firmware that could use OtherOS, I would like to try downgrading to it as well and was wondering if anyone could supply a link for the 3.15 firmware as the one in the download section no longer works.

You can go as far back as what your ps3 was shipped from the factory with I believe but really there is no reason to go below 3.15. Why would you want an inferior version of otheros when you can get the best available at the moment on 3.55?

Oh I have the newer one setup on my 3.55 install. But I just want to play around with the ps3 and thought this might be something interesting to do.

As for your first part. My PS3 when bought has 3.4 something on it, but I used an app I found that is supposed to tell you what the earliest version u could have on your system was and it said, well I forget this moment, but it was below 3.4x

Just be careful where you get your pup from. I tried the exact same thing you are doing because I was bored. I couldn't get 3.15 from here so I tried another site and almost got stuck in a loop from using a bad pup.

My Thoughts as well, which is why I am asking here hoping some trusted person on this site will upload it.

if you get the pups from here they can be trusted, still always check the hash to make sure it's legit.