Dear Customer,
Your service request : SR #{ticketno:[8200300964]} has been reviewed and updated.
Response and Service Request History:
We understand you have a question about running 2 different specifications video cards in crossfire. The result is the faster card will downclock to the slower card. It is recommended to get identical cards from the same manufacturer for performance.
For example, HD5770 700mhz gpu clock 800mhz memory GDDR5 and HD5770 650mhz gpu clock 700mhz memory GDDR5. The slower will not be able to run at the speeds of the faster card because it will be running beyond it's design specification and there the faster card will need to downlock to 650mhz gpu and 700mhz memory speeds.
In order to update this service request, please respond, leaving the service request reference intact.
Best regards,
AMD Global Customer Care