As you would know maxwell and older graphics cards doesn't support "gsync compatible". Gsync compatible is running gsync on freesync supported monitors basicly.
This is unsupported on maxwell and older graphic cards because card doesn't have displayport 1.2a specification in bios as stated by nvidia staff on official nvidia forums.
It does have displayport 1.2 but not 1.2a it can even be updated to 1.4 but it still unsupported because of lack of 1.2a (maybe gsync compatible only works with 1.2a).

So is there any chance of adding displayport 1.2a support to gtx 970 bios by modding ? Or is it a hardware thing like signals etc..

If it would be possible then it means a new life for gtx 970+ graphic cards even for gtx 780,780 ti

Thanks and have a good day !!

Adaptive Sync is software based and must be supported at runtime by driver level to work.
Hardware 1.2 = 1.2a hardware.
Nothing changed.

Nvidia doesn't support VESA adaptive sync on 900 series duo the work\license (STRATIX FPU) fee required.
Both's part will either tell about something along the "driver overhead" line or unsupported key sequence on the other.

Long story short: rev-&-nue.

So its more like a driver thing ? Can it be done through modded drivers ?

On 1.2 hardware it's more like an optional VESA specification.
The question is: can it be supported by the official channel?