Remember, most of the time the black screen appears, the laptop was just powered on
and therefore cold. I really don't think, this problem is heatpad related. Actually the pad doesn't look too bad for me. The newer graphic cards have this red glue (?) around every corner at the gpu. There has to be a reason for this modification, otherwise they wouldn't do that. My new card lies in front of me: though this red material doesn't look like this, it's really of a hard consistency.
-> Maybe it's really a kind of glue.
-> Maybe they had to fix the newer cards, because the chips on the older ones got "loose" after months/years of transport and using the laptop.
-> Maybe the contact between gpu and card module is fixed again (temporarily) after pressing 6,7,Y
Of course there's no evidence for the above theory, but I believe in it

PS: is there anybody with a new video card, who got the same problems again?