My experience with the two carts was this: if I let the system 'warm-up' (get warm to the touch) for a half hour or more, the games work. They will initially turn on with a crash after the atari logo, or some other glitchy display. When I leave the game running in this glitchy mode and let the 7800 warm up, the games work fine, although its probably not healthy for the system. I've also found that if you have been playing another game and the system is warm, then the warm-up time is much faster. I have had both Santa Simon and Pac man collection running flawless when I have warmed up the system for an hour or so.