Sim, testei em outros emuladores, como snes e master system, o problema só ocorre no Dreamcast, por isto frisei o emulador em questão. Já verifiquei as ligações e parece estar correta, vou fotografar as ligações e postar aqui.
w00t! i solved it and it was the stupidest fucking thing. Turns out i was tinkering around with the power switch scripts (to turn a button into safe shutdown switch) and since i forgot to comment the line back, and the VGA666 was taking all the GPIO pins, it was probably triggering it into shutdown. It was confusing me because i had no screen stating that the script was being triggered into running and the screen went away in a really strange way.
shit at least i solved without going insane at the pi or the vga or whatever. haven't tested the hdd but it was clear as daylight when i saw the powerswitch.sh being started at the log (should check logs more often i know). thanks anyways!