Atom-15 v16

i having problems trying to get 2 cards to work with moded atom-15 bios images
one is a 5450 and the other is an r7 250a

i can read the bios from the cards and run them through atom-15 and flash them back fine
but when i run them with a known good vga to scart its like they are out of sync and i have tried with and with out c-sync and 15kn+31khz exactly the same

any advice.