is possible?
yes.
system routerboard settings set cpu-frequency=800
estable?
I don’t know, but use 12V power supply, because some boards have problems with 24V ones and get very hot : P!
I think only RB433AH are tested to work with 800MHz, but I have many 411AH working at 800.. some 411AH are not able to work at 800 and freezes.. perhaps with 450G is the same.. test it : D!
my 450G is not working
It’s possible.. I don’t know why uses the same chip than 433AH and it doesn’t work on some 411AH, for example..