Bonsoir,  
J'ai eu u problème de carte mère après une fausse manip avec une MAJ, sur les forum officiels d'asus  
, on me propose ceci:  
 
 

On a new build you should clear the CMOS after connecting the bare basics that you will need for the OS install. You should disable all overclocking and have only one stick of memory installed during OS install also. For best results you will want to go into BIOS and set your memory sub-timings, voltage, and speed manually to stock manufacturer recommendations.  
 
A dead or weak CMOS battery will cause most boards to seem dead or act as though it has a mind of its' own. You cannot test a battery with a multimeter because even a weak battery will test close to spec voltage, so unless you have a battery tester, replace the battery with a new one to see if anything changes.  
 
There's always a posibility that the PSU is incompatible with the video card or the PSU is failing, so borrow another to test with if at all possible.  
 
If you cant get into BIOS then do some testing:  
Connect a speaker (like THIS one for example) to the system panel connector so that you can hear the POST beeps.  
Disconnect all hardware except main board power connection and the cpu+HSF.  
1.)Disconnect the power cord from the PSU and clear the CMOS leaving the battery out and jumper moved for ten minutes (600 seconds). Now try booting with no memory, but with video card installed--- you should get 'no memory detected' beep code, no beeps at all here means the video card may be faulty  
2.) try booting with no video, but with a single stick of memory installed in slot B1 (you can try all slots if no beeps, consult your manual for slot options)---you should get 'no VGA detected' beep code, no beeps at all here means that the memory may be faulty or it may have a conflict with the board---try the other memory sticks now to see if any of them produce beeps  
3.) try booting with both the single stick of memory and the video card installed-- you should get a single beep indicating a good POST---if so, go into BIOS and set the memory speed, timings, and voltage manually to manufacturer's specs  
 
If you get no beeps during 2 & 3 then I would suspect the memory. If no beeps at all then try booting the board from a tabletop, lying the board on cardboard to protect it---this will test for shorts to the case---repeat the above scenarios. If no beeps or display at all ever then I suspect hardware compatibility, so verify the installed BIOS will support the cpu. A small list of AMI BIOS beep codes can be found HERE. Some AWARD BIOS post beep codes can be found HERE.  
 
If you feel that the BIOS is corrupt, you can also try THIS. Also try naming the file the same as the ".BIN" or ".ROM" file that is in the root directory of the original Asus cd that came with your board. Don't forget that when using a flash drive for BIOS flashing, it should be formatted as fat32.  
 
You can also try a hard reset. Unplug the PSU from the wall receptacle and remove CMOS battery, then press the power button on the case for 10 seconds. Replace battery and power cord and see if anything has changed.  
 
If you power the board with no cpu installed it will reset the board to original factory defaults. Give this a try also.  
 
If all of this testing has failed and you get no POST beeps during any of this then you should call Asus tech support and suggest an RMA. Flashing with AsusUpdate may not be covered by warranty, see THIS.  
 
The board may not post until you clear CMOS, especially after a new build. Clearing CMOS forces the board to scan for connected hardware and update its stored information.  
 
Quote from PETE  
"CMOS holds details of attached hardware while BIOS stores various settings and values that apply to that hardware as well as motherboard settings. If the hardware has changed for any reason, CMOS details will not match the current setup and the BIOS values will no longer apply and will either fail or become unstable. I'd recommend a CMOS reset when installing or changing any hardware that has a BIOS value which covers just about everything short of inserting a neon light."  
 
Clear CMOS:  
1.) immediately following a new build, before power is applied  
2.) immediately following any hardware change/upgrade  
3.) after flashing BIOS  

 
C'est pour moi la dernière solution, et je n'ai vraiment pas un bon niveau en anglais...  
Je serais la personne la plus reconnaissante du monde si qqun avait la gentillesse de faire un résumé en français pour moi,  
 
Merci d'avance et bonne nuit a vous