I looked up what I was talking about earlier. Its called the pci latency timer. You need more then 64 if you want more then 4 cards on that board.
Yup this helped!

OS is Windows 7, i use all 5830's.
Last question; After setting up 92 pci latency timer the machine booted perfectly.
Unfortunate, the 6th GPU gives 200 Mhash/s, all other GPU's give 260 Mhash/s, any idea's? Replaced it with a other 5830, works now.
Thanks all!