Hello and thank any and all who can help me

I was just playing rfactor and my computer locked up, i had to manualy hard boot my machine but when the system starts post there is no vidio signal and my monitor says that the vidio cable is not attached,
I can hear windows load from listning to opining sound it make but still no vidio!

if i push the power off switch i can hear the system shut down and power off,
What up did i just blow my $400.00 MOBO.

I have put both cards in another mobo and thay work fine.
can someone help me please