Windows 7: Radeon HD 5570 turns on late

Can someone help me with my gpu Radeon HD 5570.It's working fine but every time i shut down my pc and want to turn it up again, I wait 5 minutes only for the gpu to turn on,then the system boots and everythings ok.
With the old gpu Radeon HD 4350 I had no problems like this,it turned on normaly with the system.

I would be looking at the power supply as a first step. While the 5570 only requires a 400W power supply that 500W that you have may not be giving a clean and stabile signal. If you have a buddy with a good power supply you can try swapping that ove to your for testing.