I didn't experience any problems with it disabled during the tests. In cases of a poorly ventilated Mac case this may help keep the CPU cooler perhaps. Due to some reader comments recently, I tested putting the Mac to sleep with the upgrade installed. The PCI SCSI card connected hard drive never really went into sleep mode, but otherwise it awoke from sleep fine. I never needed to change any of the default settings in over a week of use while performing tests for this review.
Many readers frequently ask if a specific C reading is too high.
Most commercial CPUs are rated for 65C operation and if you have a temperature problem you'll know it quickly in my experience - as errors in the OS will occur almost immediately when a CPU overheats. Bottom Line is that if your CPU is running too hot the Mac OS will let you know very quickly. This also allows disabling Altivec support for troubleshooting. Until early January 2000, only Apple G4 system owners had the Photoshop 5.5 Altivec plug-ins, but Adobe publicly released an updated version of them fixed bugs and improved performance. I did see noticably better Lighting Effects filter performance as shown on the Application Tests page.