Microsoft has said previously that its upcoming DirectX 12 API will make your PC more efficient. Now we know by how much: just by using DirectX, executives said, you'll see an additional 20 percent improvement in your graphics frame rate, and a drop in CPU utilisation to boot.

A previous version of this story may have underplayed the upgrade. Last summer, Intel showed off a frame rate improvement that doubled the frame rate when moving from current DirectX 11 to DirectX 12. This week at the Game Developer conference, Microsoft showed that it had eked out an additional 20 percent when using a new ExecuteIndirect feature, a Microsoft spokeswoman said.

What does this mean? During an Intel press conference at GDC Wednesday night, Bryan Langley, a principal program manager for graphics with Microsoft, put it into context.

"This is like getting free hardware," Langley said. "So if you're a gamer, and you upgrade to Windows 10, and you have that Iris Pro, it's like getting that extra kick. It may make your game go from not quite playable, to playable, from mediocre to awesome, from awesome to just out of this world."

That's a powerful argument for any PC gamer to upgrade to Windows 10. So far, Microsoft has given no indication whether or not DirectX 12 will also be made available for Windows 7, but it's unlikely. And with Microsoft providing Windows 10 as a free upgrade to Windows 7 and Windows 8 for a year after its release, it's hard to argue against upgrading.

On Thursday, Max McMullen, a principal development lead for Microsoft, outlined the technical resources that DirectX 12 would be making available to software developers. But he also noted that Microsoft has carefully recorded, anonymously, the hardware that PC gamers are using to connect to Microsoft's resources and download and run the technical previews of Window 10. McMullen said that Microsoft believes that Windows 10's DirectX 12 will run on about 50 percent of all gaming PCs today, and that it will "have two-thirds hardware coverage" by this Christmas.

"So it's going to be a great, huge platform for lots of endpoints to reach," McMullen said.

To be fair, the contrast between DirectX 11 and DirectX 12 has been shown off before: specifically at SIGGRAPH 2014, when Intel emphasized the potential power savings that DirectX 12 could bring.

McMullen used the same Intel "Asteroids" benchmark in his presentation Wednesday, but demonstrated that the frame rate increased a more modest 20 percent. But the CPU consumption also fell from 25 percent to 9 percent as DirectX 12 asked the GPU to shoulder more of the workload.

The demonstration ran on an Intel Core i7 4770R (with Iris Pro graphics 5200 installed), but McMullen didn't indicate whether Nvidia cards, for example, would see a greater improvement than hardware for AMD. The overall message was a simple one, however: if you're a gamer, you'll want to upgrade to Windows 10 and DirectX 12.

Clarification:This story was updated at 11:06 AM with additional information to clarify that the 20 percent improvement was in addition to the frame-rate increases that Microsoft has disclosed previously. A Microsoft spokeswoman also disclosed the hardware Microsoft ran its tests upon.