You need to do a clean boot and Driver Fusion / CCcleaner wipe of the previous GPU drivers.
This is a fairly common occurrence.
The 780 can't use older drivers at all.
Steps.
type "msconfig" and setup clean boot state.
http://support.microsoft.com/kb/929135
Uninstall drivers through control panel.
Reboot into Safe mode.
Run Driver Fusion - remove all Nvidia files. - you can keep C:\Nvidia folder though as it just has the extracted drivers.
Boot back into windows normally. You should still be in clean boot state at this time.
Optional - run CCcleaner
Check that any Anti Virus program is not currently running, or pause, or shutdown for now.
You should still be in clean boot state.
Now Install latest Nvidia Drivers.
reboot.
msconfig - to go back to normal startup if you want.
Happened to me too when first installed my 780 from my GTX470 - even after uninstalling previous drivers through NV tool.
Done all of this but exactly same issue. Cannot process three frames of a game before a crash.
Thanks though. Will try cards individually and then update bios.