Game's system requirements?

I understand this might be an odd question, but it’s something that just struck me and I couldn’t find any information about:
How do I determine the system requirements for the players (or testers) for a my game?

You should have a general idea about what they will be based upon the performance your team gets with their rigs on different graphics settings. From there you can create more precise specifications from the data alpha testing on a wider range of hardware will give you. A lot of it depends on what your FPS target is, is your min requirement going to be enough for 30 FPS? 60 FPS? A low end 1GB DX11 GPU like the GTS 450 should be enough to run any game fluently on low settings and keep 30 FPS, provided the CPU can feed it.

Ah I see, that’s a good suggestion, but atm im a 1 man team running high end hardware, little user end comparison there.
I was kind of hoping there was some kind of ‘suggested/supported hardware’ information or something, like if I don’t use any fancy graphics stuff the user would need a less fancy graphicscard.
Guess any testing will have to provide the hardware information aswell then.