If "IDE configuration" in BIOS is set to "AHCI mode", Windows 10 setup is unable to start. BIOS boots from bootable usb drive, and the blue Windows logo plus the progress wheel are displayed forever. If I then go into BIOS settings, and set "IDE configuration" to "SATA mode", Windows 10 setup starts a few seconds after the Windows logo and the progress wheel. This problem doesn't occur with Windows 7 setup from bootable USB drive. The motherboard is Asus M2N-X with nForce 520 chipset. I use SSD, so I need "AHCI mode". So in AHCI mode, I can install Windows 7, but I can't install Windows 10. Why is that?
@explorer11: According to my own experiences the Win10 Setup may have problems with some optical drives, if they run in AHCI mode. Here is my advice: Unplug all storage and optical drives, which are connected to the SATA ports, except the target SSD. Then repeat the OS installation in AHCI mode.
Do you have Legacy USB Support enabled? Bootable USB also needs to be created to support it, I use Universal-USB-Installer just for that (laptops).