Crossfire Boot and Restart Problem

Hello,

 

I Use 2 MSI R9 280 Gaming 3G Cards in Crossfire on a ASRock z97 Extreme 3 Mainboard.

Powersupply with 750 Watt Corsair RM 750i.

Crossfire works well with and in Games.

Win 10 pro

The Problem is if I shut Down the Computer an Crossfire is still on I get a Boot Problem. It starts booting and Stops after a few seconds.

When I Reset it starts and boots into windows.

When i restart windwows it hungs in the Restarting Screen.

I have to reset then.

When Crossfire ist off everything boots well.

 

This problem occured from the beginning.

I Allrwady changed the Motherboard for a Gigabyte z97P-D3. It was the same Problem.

 

Can sombodey help?