According to what we could gather from Nvidia's official bundle page, the Gears of War Geforce GTX Game Ready bundle is open to most the countries and runs from September 20th to October 30th, or until Nvidia runs out of free download codes, and is, as always, limited to select retailers/e-tailers.
While the game will be bundled only with Geforce GTX 1080 and GTX 1070 graphics cards, the system requirements are a bit lower so you will need Geforce GTX 750 Ti for minimum specification and 1080p resolution while GTX 1060 will get you in line with recommended specification and should be enough for 1440p resolution.
According to Nvidia, for an "ideal" 4K (2160p) Gears of War experience, Microsoft actually recommends the Geforce GTX 1080 and you can check out the video of 4K gameplay on GTX 1080 below.
As noted earlier, the PC version of the game will have plenty of graphics settings including anti-aliasing, ambient occlusion, level of detail, various effects, lighting, shadows and textures settings. Of course, Nvidia recommends Geforce Experience software which will tweak those with a single click, giving a balance between performance and image quality.
In case you are shopping for a GTX 1080 or GTX 1070, be sure to check out the Gears of War Nvidia Geforce GTX Game Ready bundle page and in case you missed it earlier, Gears of War 4 will launch on October 11th on both PC and Xbox One.