Why can't i install windows via USB connection, would it work if connected to a SATA port?

Windows 8 and Windows 10 can be installed to a USB flash drive or suitably fast SSD. The official method only supports Enterprise and Education versions, and doesn't work on newer versions of Windows 10. Third-party tools like Rufus can make a bootable installation with other editions.

Windows 7 doesn't support installation to a USB attached hard drive or flash drive. There's a tutorial here that can supposedly get Windows to Go to work.

http://agnipulse.com/2012/11/windows-to-go-all-ver...

If you're just trying to do a normal installation of Windows 7 from a bootable medium to a hard drive, and you have the option to connect it via SATA, I suggest you do so. 

you CAN install Windows 10 from a USB flash drive.

just copy the files to it and boot from it.

you may need to change your BIOS boot settings.

Go to what passes for a Bios on your computer and make sure that USB boot is enabled. 

You should be able to if you've made an install disc on USB and select USB as boot drive.

It would help if you could explain what happens when you try to install via USB, are there any error messages? etc.

Which windows version are you trying to install? Windows 7, 8 or 10 and how did you create the USB? did you set the BIOS to Boot off the USB?