Trying to get ATI Radeon HD 5770 working in 2006 MacPro 1,1

Question

Hi, all.
In the last week or so my GeForce 8800GT appears to have died. After the machine's been up for a while I get flickering, black bands, garbled pixels and colors, and eventually a crash of the UI subsystem (although the machine stays up and can be SSH'ed into after the UI goes away). The machine is also likely to hang during boot with the 8800 in place.
Swapping in an old Apple-supplied, GeForce 7300, the machine boots and runs fine.
Seeing a number of threads in which people have managed to get the Apple-supplied Radeon HD 5770 upgrade kit working in 2006 1,1 models of the Mac Pro, I ordered one.
My system's specifics are:
MacPro 1,1
Boot ROM: MP11.005C.B08
SMC: 17f10
It's running OS X 10.6.4 and the Snow Leopard graphics update is installed.
My problem is this. When I put the 5770 in, and connect its power cable (using either the power cable from the 8800 or the new cable that came with the 5770), and connect my 30-inch Cinema display to the DVI connector on the back of the 5770, the monitor never lights up.
I don't see the gray screen, or the Apple logo. Disk chattering is consistent with a clean boot, and if I whack on the keyboard I can hear the sounds from the login window. I can also remote desktop into the machine. When I do, I find that it has booted successfully and the in System Profiler under "Graphics/Displays" that there is only the message "No information found." There's no mention of the Radeon, or the Cinema display.
The fan on the card does spin, so at least it seems to be getting power.
Any suggestions? It sounds like many folks with configurations about the same as mine have had relatively little trouble getting the 5770 working on their 1,1 machine.
The fact that I never see anything but a black screen makes me wonder if there's more going on here than just software, since I'd guess that the initial gray screen and Apple logo are provided by the boot ROM using lowest common denominator VGA functionality common to all cards, and that no real systems software has loaded or run by that point.
Guesses? Suggestions? Is it likely I got a DOA 5770? Or might my Mac Pro be less up to the task than the other 1,1 machines that have succeeded? Or have I done something wrong, or forgotten to do something?
Any and all pointers are appreciated. If I can't get this 5770 to work my options may be going back to the 7300, or paying Apple $440 for a repair replacement of the 8800, which is a painful sum to fork out for a slow, several year obsolete NVIDIA card that doesn't have a sterling reputation for longevity.

Answer 1

Ah, interesting. Here's what I get when I boot with the old GeForce 7300 plugged in.
System Profiler shows no extensions with "ATI" in the name. I'm not sure if this is to be expected though. Does System Profiler -> Software -> Extensions display the kexts installed on the system, or only those that the kernel decided to load at boot time? If the latter, I guess I wouldn't expect to see them. If the former, then might there be some registration step I need to do to tell the system that the ATI kexts are present and able to be loaded?
As for the presence of the extensions, if I look in /System/Library/Extensions, I find the following files when I do an 'ls -lF | grep ATI'...
ATI1300Controller.kext
ATI1600Controller.kext
ATI1900Controller.kext
ATI2400Controller.kext
ATI2600Controller.kext
ATI3800Controller.kext
ATI4500Controller.kext
ATI4600Controller.kext
ATI4800Controller.kext
ATI5000Controller.kext
ATIFramebuffer.kext
ATIRadeonX1000.kext
ATIRadeonX1000GA.plugin
ATIRadeonX1000GLDriver.bundle
ATIRadeonX1000VADriver.bundle
ATIRadeonX2000.kext
ATIRadeonX2000GA.plugin
ATIRadeonX2000GLDriver.bundle
ATIRadeonX2000VADriver.bundle
ATIRadeonX3000.kext
ATIRadeonX3000GA.plugin
ATIRadeonX3000GLDriver.bundle
ATIRadeonX3000VADriver.bundle
ATISupport.kext
So lots of ATI-related goodies. The dates are all either Aug 2 or Aug 6, so I'm guessing they came with the Snow Leopard Graphics Update, which I think was released just after those dates.
I'm getting ready to return the card and try another, but will hold off another day or two, since it still seems plausible that there might be a software issue lurking...
Thanks again for your help,
Jerry