Thanks a lot for that response ! I've checked the LEDs and when turned off my iMac has only LED1 ON. When turned on, it has LED1, LED2 and LED3 ON... Any additionnal clue with thoose datas ? EDIT: I've tried to start the machine with the flat 27" screen unplugged and... mystery the 3 led's are still ON ! Wasn't the 3rd led supposed to be communication with screen ? I'm confused... any clue would be very very helpfull tranks !
I manage to replace my iMac HD by an SSD and it works really great ! The probe was indeed an issue... fixed by cutting the Hardrive side's of the probe and connecting the two wires together. A piece of "electric proof" scotch and here you go ;-) You don't monitor the drive temperature anymore but you can always do it later :p