# Windows – What does Windows 10 Setup do when installing “both” x86 and x64 architectures

64-bitwindows-installationx86

On a Running 64 bit programs on a 32 bit system answer there's this screenshot:

What does the installer do if you select Both as architecture?

I don' think there's any way of having a both x86 and x64 system – without it being an x64 system itself. The alternative could be installing two OSes – but I don't see how can a single installer do both and still have a decent UX.