You're sure it's a 2.0 and not a 2.1 version ?
 

rdc85

Honorable
As i remember The "2.0" can deliver up to 75 watt power and "2.1" can deliver power up to 150 watt, so some card may work some card don't...

well after read the version history in wiki it also stated that.. radeon 6670 ddr5 is low powered card it a good posibility it will work with 1.1