I have this same problem plus a fan is not working. I just replaced the fan unit (it comes with two fans in an aluminum housing.) Still doing the same thing and the same fan is not working. Got a bad feeling that it is a $600 MoBo. Sager won't send me one either. Very protective of the MoBo's. I have to send it off to them with a $80 installation fee and $40 for shipping too. They say it may not be the mobo, but it is quite likely. Anyhow it will be gone for 10 days. I got an RMA number with an open time to use it, since I am out of warantee. I can mail it in any old time and the RMA will be good. I am not having any problems other than the blinky lights. As long as I don't play any intense 3D games it stays plenty cool. So I may hold off til after Christmas to mail it in.
So in my case the blinky lights are telling me that one of the fans is inop, not that it is overheated.
P.S. I had to take the whole computer apart to swap out the fan unit. Meticulous screw organization insured that it all went back together happily. The service manual is a godsend for this operation too.