I have a A8N-SLI Premium which I have been messin around with recently, there is an option in the Bios for SLI mode, it has the choices of Auto (default), Single Video Card, Dual Video Card. Try setting it to Dual Video before putting the connector in. The Options are in Advanced > SLI...
Updating the controller driver to standard will definately work to, it is a method I have used countless time to migrate an installation.
Oldie's suggestion of using the Windows cd to perform a repair install will also perform the same function which will ultimately also work for you.
Be...
If your hard drive is IDE the trick is to go to the device manager to IDE Controllers and update your controller driver to Standard Dual Channel PCI IDE Controller. Do this on the original computer before you move the drive over to the new machine, it should then startup on the new machine...