I'm running Windows 10 64 bit with a custom built PC i put together several years ago. Here are the specs:

XFX nForce 780i 3-Way SLI (sli inactive)
NVIDIA GeForce 480 (i think that's an 8, might be a 6) graphics card
8GB ram (4 2GB sticks)
Intel Core 2 Duo Q8200 processor

I'm running BIOS P06, and I'm having all storts of issues after upgrading to windows 10. My graphics card is crashing constantly, which i believe is a driver issue, but the other issue is that virtualbox won't run any 64 bit VM. I keep seeing that i need to enable virtualization in my BIOS, but the option isn't even available. I've seen other users say it is, so I figure an update is needed.

I downloaded the upgrade from here for the P09 and verified it was for my motherboard, and installed a Bootable DOS USB with that BIOS bin file. I booted to USB and it ran through the whole process of flashing my BIOS and installing the new one successfully.

I powered off my machine and removed the CMOS battery and unplugged the power cable for 5 movies minutes. I boot it back up, enter the BIOS, and see absolutely no difference.

Upon booting back into Windows, i checked CPUID-Z and it says I'm still on P06, and virtualbox still won't run 64bit. I've run through the process four times now with the same results.

Any help would be extremely beneficial because I'm seriously about to take this computer out back and fill it full of lead.

Welcome to the forums..If you're having issues, you could try NVIDIA System Tools which should add an NVIDIA System Update section to the NVIDIA Control Panel..From there you can update the BIOS within Windows using the .bin file from EVGA..I can install NVIDIA System Tools on Win10 but it did not install the NVIDIA System Update add-on to the NVIDIA Control Panel because, well, I don't have an NVIDIA-based mobo..But it worked on my old EVGA 790i FTW..After the update, uninstall NVIDIA System Tools and restart your PC.
 
Or you might try Rufus to create the USB drive..Or use ImgBurn to create a CD from the BIOS .iso file..One of those methods should surely fix you up.
 
Win10 might not work/work so well on the old board though like RJohnson11 said.
 
The BIOS version should be shown on the first POST screen like Release Number i780P06 (or p10 or something similar)..The BIOS version is the last part of the Release Number..You can pause the POST screen by pressing the Pause/Break keyboard key and resume POST by pressing any key.