On Jul 3, 2010, at 1:46 PM, Jonas Ulrich wrote: > Ok I though it was fixed, but my 17" 1.8GHZ iMac G5 overheats and the fans > rev way up if I even check my e-mail. If it just sits with nothing open it's > fine. Any help would be greatly appreciated.
It sounds as if your iMac's thermal sensor(s) are getting faulty information. Here's what Apple says in the service manual for the ALS model, 17-inch: Fans are running at a constant high speed If the fans on the system are running at a constant high speed, or ramp very quickly to high speed and do not vary this speed once reached, the fans are most likely receiving incorrect thermal input. In these cases you should use the following steps to resolve: 1. Reset the SMU ... and then test to see if the fans still exhibit the issue. 2. Boot from the iMac G5 Install DVD or another iMac G5 of the same type in FireWire Target disc mode and see if the issue persists. If the fans run normally here, reinstall the system software. Be sure to give the system enough time to recreate the issue when booted to these other volumes. 3. Verify that the hard drive sensor cable is plugged in correctly. If necessary, replace the hard drive sensor cable. 4. Replace the hard drive (the hard drive includes the sensor on the hard drive carrier). 5. Replace the main logic board. I don't remember what you've done to your iMac, but you also might want to check the quantity and quality of the thermal paste or pads between the GPU, CPU and the bridge chip (all are under the big G5 shield, which means you may have to disassemble your iMac to check). It's possible that a previous owner or service person either didn't renew the thermal paste/pads, didn't use the correct ones, or left one out. I've seen all of these happen, which is why I never take anything or anyone for granted when diagnosing a new-to-me Mac. If any logic board capacitors were replaced, it's possible that one or more might not be correctly soldered in place, which could be causing the fan problem. I've replaced caps on iMac G5s, and have experienced ramped up fan noise until I resoldered several caps again. Have you run the Apple Hardware Test, Quick and Extended? This might give you a clue. Jim Scott -- You received this message because you are a member of G-Group, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/g3-5-list
