1) Your MB is the P67.
2) Supporting GPU or not, which does not related with the BIOS.
2) If the MB does not support the "new video card", there are only the situations, which is A) the GPU is the AGP video card. B) some of PCI-E 2.1 cards have issues with the older PCI-E 1.0 X16 slots. But the P67 has the PCI Express 2.0 Interface. 3) the case does not have enough space. 4) PSU does not have enough juice to power up the GPU.
If you want you can download the BIOS into the USB drive, then you can update the BIOS. But if your PC run fine then don't update the BIOS, in case something wrong during the update. Then the PC will not boot again. Only you need use the new CPU then you have to update the BIOS to support the new CPU like the 3rd generation Intel CPU.