Microsoft has added DirectX 12 with the latest Windows 10 Technical Preview that was released today. Until today, DXDIAG reported DirectX 11 in the Windows 10 Technical Preview. At the moment, there has not been any drivers or software released for it, and the SDK is also no-where to be found. Really, all this means is that one barrier has been lifted, leaving the burden on hardware and software partners (except to release the SDK, that's still Microsoft's responsibility).
No-one needs to know how old my motherboard is…
Note: I have already experienced some issues with Build 9926. Within a half hour of using it, I suffered an instant power-down. There was not even enough time for a bluescreen. When it came back, my Intel GPU (which worked for a few minutes after the update) refused to be activated, along with the monitor it is attached to. My point? Not for production machines.
Update: Looks like a stick of RAM (or some other hardware) blew, coincidentally, about 30 minutes after the update finished, while the computer was running, which also confused my UEFI settings. I haven't got around to troubleshooting much, but it seems like a weirdly-timed, abrupt hardware failure (BIOS is only reporting half of the RAM installed, iGPU is "enabled" but without RAM associated to it, etc.).
The interesting part, to me, is how Microsoft pushed DX12 into this release without, you know, telling anyone. It is not on any changelog that I can see, and it was not mentioned anywhere in the briefing as potentially being in an upcoming preview build. Before the keynote, I had a theory that it would be included but, after the announcement, figured that it might be pushed until GDC or BUILD (but I kept an open mind). The only evidence that it might come this month was an editorial on Forbes that referenced a conversation with Futuremark, who allegedly wanted to release an update to 3DMark (they hoped) when Microsoft released the new build. I could not find anything else, so I didn't report on it — you would think that there would be a second source for that somewhere. It turns out that he might be right.
The new Windows 10 Technical Preview, containing DirectX 12, is available now from the preview build panel. It looks like Futuremark (and maybe others) will soon release software for it, but no hardware vendor has released a driver… yet.