Graphics Card Problem HP Probook 4730s Windows 10?

I have upgraded from Windows 7 to Windows 10 on my HP Probook 4730s.

Windows 10 has found both graphics cards and has installed drivers for them. (An onboard Intel GPU and the AMD Radeon HD 7400M.) The screen resolution is correct.

The problem is that when booting up the machine shows a black screen for about 30-60 seconds before the login screen appears. From what I have managed to find out this is due to Windows 10 seeing both graphics cards. When I do turn off the Radeon Card the machine starts properly, no 30-60 wait, so I would like to leave this card turned off.

Co-incidentally with Windows 7 (my old OS) I turned off the AMD Radeon HD 7400M card because I didn't need it and it made the fan noise louder. Windows 7 worked perfectly.

With Windows 10 I cannot turn of the AMD Radeon card because if I do the Intel card produces a strange screen resolution. I think the driver is not supported by Windows 10. The card is listed in Device Manager as Intel(R) HD Graphics 3000.

What can I do to fix the issue with the 30-60 second wait in black before the login screen?