Quote Originally Posted by nachthymnen View Post
Many tks for all!!
Probably I'll send back in RMA and I'll buy a new VGA

P.S: sorry for my "camping" english
If using all stock voltages the issue is probably ram voltage since switching ram slots allowed the board to boot. From the sound of things the BIOS most likely is being corrupted because of this. I have used at least 5 different types of ram and with the board properly configured the slots used make no difference when booting.

U4 is not a valid code. If a long CMOS clear will not bring it back an RMA is going to be your only option.