I have a G4 Dual 450 and replaced the AGP Rage pro128 by an AGP ATI Radeon Mac edition (32MB) ,(the first that came out, just bought it second hand) And I also bought the PCI Radeon 7000 , also ATI and 32 MB for a second display, Everything works fine, the QuartzExtremeCheck-1.1.app (http://www2.entropy.ch/download/QuartzExtremeCheck-1.1.app.sit) told me the AGP display had Quartz extreme, the PCI not, I enabled it with PCI Extreme! (http://pages.cthome.net/zacks/pciextreme.sit) And both run now Quartz extreme everything is OK my sleep is OK I alsoupdated to the latest ATI driver: radeon-0210 (http://pdownload.mii.instacontent.net/ati/drivers/RADEON-0210.hqx) Hope this can help somebody? Danny