Something tells me that Microsoft doesn't feel all too inspired to bring Direct X 12 to, say, Windows 7 anytime soon.
Back in the '90s, when you couldn't traverse through a college campus without the violent echoes of Metallica's "Enter Sandman" accompanied by the anxious clicks of a Doom deathmatch, Microsoft reigned king over PC gaming.
With Intel getting serious about integrated graphics performance with their upcoming Haswell graphics architecture, they are now starting to release more frequent video driver updates, too.
However, you can generally get updated graphics drivers from your graphics hardware manufacturer’s website: You will have to select the exact model of your computer’s graphics card, which is displayed in the Device Manager window.
Secondly, Windows 10 – as of this writing – is the only OS that currently supports Direct X 12.
Microsoft's new graphics programming interface is said to improve games' speed, reliability and power consumption.
If your graphics hardware is five years old, it’s very likely that optimized drivers for it are not longer being released.
How long your hardware is supported is up to its manufacturer.