Try to make binary patch for ATIRadeon9700.kext.
Extract file ATIRadeon9700.kext/Contents/MacOS/ATIRadeon9700 to any place you like.
Make the follow
perl -pi -e 's|\x66\x3d\x4e\x4a|\x66\x3d\x55\x59|g' ATIRadeon9700
perl -pi -e 's|\x66\x3d\x48\x4a|\x66\x3d\x55\x59|g' ATIRadeon9700
I assume DevID=5955 - last digits in the string in reverse order.
You need to do both commands!
In some versions of ATIRadeon9700 it is not work. In this case you need other commands
perl -pi -e 's|\x3d\x4e\x4a\x00|\x3d\x55\x59\x00|g' ATIRadeon9700
perl -pi -e 's|\x3d\x48\x4a\x00|\x3d\x55\x59\x00|g' ATIRadeon9700
Then replace original file with patched, repair permissions and try!
on the first boot every change on the screen took 10 seconds. like when you type (rather fast) in terminal "sudo -s <return>", the output remains "$" and waits for 10 seconds, then changes to "$sud", then waits for another 10 seconds, then changes to "$sudo -s" and after yet another 10 seconds actually asks for password. after reboot everything appears to work smoothly as if there's no atiradeon9700.kext at all, but system profiler reports "core image: NOT supported", "quartz extreme: supported" and detects vram size correctly (128 mbytes) and i've noticed some glitches when scrolling a document in textedit.
it's symptoms ole2 noticed in early january, but me — for the first time.
you may check dmesg and ioreg (notice ati1slice working)