Are you trying to suspend and resume at the console?
On computers without xorg, there is only console.
Suspend/resume then always results in no signal from the Nvidia card.
This indicates that the state save/restore BIOS functions do not do what they should do.
If there is no way to get around this problem, the information on the FreeBSD hardware compatibility page should be updated accordingly. (-> https://wiki.freebsd.org/Graphics#NVidia_.2F_GeForce_Graphics )
In addition to that, the lack of these BIOS functions break suspend/resume for Nvidia cards on computers with xorg.
The developer of the vesa.ko driver explained this issue:
The root cause is NVIDIA does not really support VESA BIOS
re-POST and save/restore state calls. It just checks few
bits and returns immediately if they are set/clear. I
have a feeling that they intentionally did it to make
reverse engineering harder. On top of that, they don’t
provide any information to improve the situation.[/code]
Here is the link: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=224069#c9
Personally, I think Nvidia should pay for, respective sponsor implementing the workarounds necessary to fix the issues resulting in selling cards with incomplete VGA BIOS, if the above statement is true.