Bon, eh bien la panne semble se confirmer à froid.
Ce matin, après plusieurs heures d'arrêt complet du G5, il m'a été impossible d'obtenir quelque chose à l'écran après démarrage normal de la machine: écran noir!
J'ai donc fait un reset nvram (alt-pomme-p-r et attente de 4 boing successifs) sans que ça n'améliore quoi que ce soit.
Je vais aller voir dans la kbase Apple, des fois que ce problème serait répertorié, mais je doute.
Comme je me vois mal racheter une carte video sans savoir si ça va corriger la situation, je pense que j'en viendrai à laisser tourner ma machine en veille la nuit [d'ailleurs il faudra que j'essaie de le faire cette nuit... on ne sait jamais, peut-être que la ideo ne voudra pas se réveiller dans cette situation là non plus...]
Précision: même en allant jusqu'à un boot complet une première fois, la video ne s'est pas remise à fonctionner normalement au démarrage suivant. Il m'a fallu 2 démarrages avec séquence de boot complète et écran noir avant qu'au 3ème démarrage la vidéo se mette à fonctionner normalement
MAJ:
Voici ce qu'il est dit concernant ces symptômes (pas de video au démarrage) chez Apple
CITATION
My Mac starts up, but there's no video
If your Mac starts up normally (you hear the startup sound, as well as fan and drive noise) but you don't see any color or video on the display, try these steps, one at a time, until you resolve the issue.
If you have a Mac with a built-in display (iMac, eMac, iBook, PowerBook):
1. Reset the computer's PRAM (parameter random access memory):
1. Restart the computer and immediately press and hold the Command, Option, P, and R keys simultaneously.
2. Continue holding these four keys until you hear the startup sound for the second time.
3. Release the keys to allow your computer to start up normally.
2. Try resetting the computer's PMU (Power Management Unit). The reset instructions are different across each Apple computer model. To get specific instructions for your computer, go to our Apple Service & Support site and type computer reset pmu (where computer is your computer model—for example, iMac G5 or PowerBook) in the Search box to find articles that show how to do this.
3. Start up your computer from the Software Install disc:
1. Insert the Software Install disc that came with your computer into your Mac.
2. Restart the computer and immediately press and hold the C key to start up from the disc.
3. If you see video when your computer is started up from the disc, you may have corrupted software. Use the Archive and Install feature of the Mac OS X Installer to reinstall Mac OS X. This kind of installation gives you a fresh version of Mac OS X, but you won't lose any data from the computer because it gets archived.
4. If you tried all the steps above but the computer still won't display video, call in the cavalry.
If you have a Mac with an external display (Power Mac, Mac mini):
1. Make sure that your display is turned on and has power, that the display's power cord is plugged into a working wall outlet, and that it's properly connected. (To check if the wall socket is working, plug in a lamp or other electrical device.)
2. Make sure that the video cable's connections to your computer's video display port and to the monitor are secure.
3. Examine the pins on the video cable connector to make sure they aren't bent or damaged in any way.
4. If you have an extra working display available, connect it to your computer. If you see video after doing so, replace your old display.
5. Reset the computer's PRAM (parameter random access memory):
1. Restart the computer and immediately press and hold the Command, Option, P, and R keys simultaneously.
2. Continue holding these four keys until you hear the startup sound for the second time.
3. Release the keys to allow your computer to start up normally.
6. Try resetting the computer's PMU (Power Management Unit). The reset instructions are different across each Apple computer model. To get specific instructions for your computer, go to our Apple Service & Support site and type computer reset pmu (where computer is your computer model—for example, Power Mac G5 or Mac mini) in the Search box to find articles that show how to do this.
7. Start up your computer from the Software Install disc:
1. Insert the Software Install disc that came with your computer into your Mac.
2. Restart the computer and immediately press and hold the C key to start up from the disc.
3. If you see video when your computer is started up from the disc, you may have corrupted software. Use the Archive and Install feature of the Mac OS X Installer to reinstall Mac OS X. This kind of installation gives you a fresh version of Mac OS X, but you won't lose any data from the computer because it gets archived.
Par ailleurs, sur les forums du support Apple
Apple: black and screen and death on a des témoignages qui incitent à penser que la carte vidéo arrête de fonctionner lorsqu'il fait froid - comme maintenant- et qu'on peut remédier au problème en réchauffant la carte vidéo avec un sèche-cheveux!
Ceci expliquerait que mon problèm disparait après plusieurs redémarrages... Les différentes tentatives auraient l'effet de réchauffage de la carte vidéo!
