Apple

All four lights are on on each of the memory boards, even for the slots that are not populated. Also, the over temp CPUA and CPUB light is on on the logic board. I used temperature monitor and the readings seem normal. Is there any way to see what is going on, or is it just an ECC error and the machine needs to be reset? (It has been up since I moved in early May...). I don't want to lose any clues about impending doom with an unnecessary reboot.


I have been playing UT3 in vmware fusion (runs great!) for a few hours, which maybe overcooked something. It (UT3) is running now but still the temps seem normal. All the fans are working.

Numbers look good to me. Apple's temp specs are usually a lot higher than what you're seeing.

Perhaps a PRAM / SMC reset is in order to clear the warning lights? If you are really worried there are memtest programs for OSX...

shut it down and hit the SMC reset button, it's been running for an hour or so without the lights coming back on. Must be gremlins... if it comes back I'll post an update. It was still running fine but I could see the lights through the grille in the dark room, no idea how long they have been on.

I've never peeked inside a running Mac Pro, but on the old PowerMacs they had a red LED next to the RAM turned on all the time. On those machines it was harmless and didn't really mean anything if it was on. They probably did this as a warning that the machine is running and you shouldn't replace RAM or something.

What model was that, Shade? My quad doesn't have that. In fact, the red light should extinguish after POST.

I've seen this on both Sawtooth and MDD PowerMacs.

Looks like they've changed the meaning of that LED on the newer models

That might be. I haven't looked inside my Sawtooth or MDDs when they're running, but on the quad the red LED lights briefly on startup and then goes out (you can see it through the front of the case) and I think all the G5s are like that.

Apologies to the Mac Pro owners.