openSUSE 13.1 Milestone 2 and Kubuntu 13.04 on 3 boxes with kernels 3.9.0+ and 3.10.0-rc.
No problems with ION, GTX560 and GTX560 Ti on boxes using 3.10.0-rc7 kernels and driver 319.23.
I replaced the 8600GT with a GTX560 which works.
Everything in Xorg.0.log looked OK up to the point where no screens found.
Unfortunately the log has been overwritten.
The remaining 2 boxes with the 8600 GT are using the nouveau driver.