I have the shit "Could not find supported display mode" issue and i "googled" above 3hrs to find any solution.

Nothing. I tried to set the resolution to 800x600.
I tried to activate only one Screen.
I tried both together.
And i tried other shit with "dgVoodoo" and and and... .. . .. . . .

Im rly pissed off...

If you want to get your money back you should contact the customer support and describe your problem. If they can't fix it you will get your money back.

which monitor(s) are you using?
and which video card? (nvidia? amd?)

have you tried physically unplugging all but one monitor? (can't always trust software)