imac switching off /Intermittent power problems

[ranj]

Dear All

 

There is one particular iMac in our school which seems to suffer from intermittent power problems.

 

We actually sent it to Apple because we thought it had a power supply failure and it seems that wasn't the issue and the Mac came back to us unrepaired.

 

This iMac can be very temperamental, sometime you can turn it on and it will boot up fine but then after 3-10 minutes the mac will just switch itself off, sometimes it won't switch on at all, and sometimes it comes on but you can hear the fan whirring and is fairly loud and no display appears.

 

We consulted Apple about this and they said it may be that we need to reset the system management controller and we can do this by following these instructions:

 

Intel-based iMac, Intel-based Mac mini: How to reset the System Management Controller

 

This solution doesnt seem to work for us, at the moment it just refuses to come on but about 2 hours ago I managed to get it working for it to power off again.

 

Do anyone have any other solutions we could try? if I manage to power it on, is there anything that can be done in verbose mode to diagnose this problem? More importantly have any other Mac users seen these problems?

 

Any advice fellow edugeekers can provide would be most appreciated

[linkazoid]

We experience similar problems, but it happens to a whole suite.

 

The whole suite will just power off at the same time, no messages alerting of a shutdown, and nothing in the console as to what's happened.

 

We are beginning to think that its a power problem as it an older part of the school. Our electrical contractors are investigating.

 

Mike