I'm in the process of testing this for a Win7x64 system running 4x6770 (Sapphire). Everything seems to work fine except the program will not detect the fan speed of the cards (reports N/A), nor allow me to set the fan speed. This is peculiar as I can set and monitor fan speeds with the ATI Catalyst and MSI Afterburner tools.
I'll post program output later today as I am not at the computer with the hardware right now.
Here is a quick output dump showing the functionality working with a Sapphire 6770, albeit no fan control or speed reporting. I've been able to change multiple GPU properties in the 4x6770 system, but I'll only show the dump for one. If eligible, you may send the testing credit to 1BrcSXF3te8YNvfwDp9yoFebvZNkxGRe7i.
thanks! refund sent. no fan control on x770 systems for now.