Yeah, be sure you have the latest BIOS even if that's not the issue. If you have any settings, they'll all get reset to factory defaults after an update, so be sure to take note of the things settings you need before updating.
Also, when switch to the new GPU, are you plugging your monitor into it rather than into the motherboard? The ports on the motherboard won't work once disable onboard graphics. Just something to remember. Try it with the new BIOS.