Thank you GB for the tip.
I found the info to change frame buffer personalities and ports. I tried many. Some had an effect on the way dual monitors booted, but none changed the 3d speed test in NovaBench. I suppose it's not really a frame buffer personality issue.
I also discovered "ioreg" command in Terminal. It shows what personality you have. This is with AtiConfig=Hamachi
| | | +-o IOPP <class IOPCI2PCIBridge, id 0x10000021a, registered, match$
| | | +-o PEGP@0 <class IOPCIDevice, id 0x1000001c1, registered, match$
| | | | +-o RadeonSensors <class RadeonSensors, id 0x100000227, regist$
| | | | +-o AMD7000Controller <class AMD7000Controller, id 0x1000002e5$
| | | | +-o ATY,Hamachi@0 <class AtiFbStub, id 0x100000323, registered$
| | | | | +-o AMDFramebufferSI <class AMDFramebuffer, id 0x100000327, $
| | | | | +-o AGPM <class AGPM, id 0x10000032a, registered, matched,$
| | | | | | +-o gpu-control <class IOService, id 0x10000032b, regist$
| | | | | | +-o IOHWControl <class IOHWControl, id 0x1000003c7, re$
this is without AtiConfig
| | | +-o IOPP <class IOPCI2PCIBridge, id 0x10000021b, registered, match$
| | | +-o PEGP@0 <class IOPCIDevice, id 0x1000001c1, registered, match$
| | | | +-o RadeonSensors <class RadeonSensors, id 0x10000022f, regist$
| | | | +-o AMD7000Controller <class AMD7000Controller, id 0x1000002d6$
| | | | +-o ATY,AMD,RadeonFramebuffer@0 <class AtiFbStub, id 0x1000003$
| | | | | +-o AMDFramebufferSI <class AMDFramebuffer, id 0x10000032c, $
| | | | | +-o AGPM <class AGPM, id 0x100000330, registered, matched,$
I'm guessing (blindly) that it just reads the GPU's Bios. I installed Yosemite with a DSDT this time, hoping I might find a patch. I've read solutions using Clover but I'm not ready for that.