...last year I purchased a 512MB model B, but had problems where it would shutdown immediately upon hitting login giving no time to write logs or read and "textual" output.
Other things came along in the intervening time period and I haven't had a chance to test this out, but I came up with a theory in the meantime as it annoyed me enough to think about it from time-to-time given that I was using the same PSU as with the older 256MB model B which worked just fine:
Theory: I purchased the vid codecs for the 256MB model B, and setup the card, however I now realize that I was using that same card trying to boot the newer 512MB model B. Is it likely(or have I missed it somewhere) that the codec authorization code rather than just failing to load was causing the immediate shutdown behavior of the 512MB model B when it discovered that the serial # didn't match the authorized model B for the vid codecs?
IF so, I really wish that this behavior was changed(if possible) to just having the vid codecs fail loading and printing a message into the logs rather than making a different piece of hardware essentially inoperable.
(Downloading a few latest copies of 3 distros ATM to test this with later tonight maybe, as I have a simplistic project that I want to try out if I can get the supposedly problematic board to work... it was a 512MB China board purchased via Newark/Element 14 if that makes any difference...(and I never tried riscos on it that I can recall -- had another project that I used something else for instead as it was working and I didn't want to waste extra time troubleshooting at that time...))