D975XBX2 can't boot after FSB increase

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It happen before because I did a big jump for OC the FSB frequency...I had a second mobo and change it.

Then, I was running fine and stable on the second mobo at FSB 333MHz with 667 MHz memory.
I decide to try 2 stick of 800 MHz memory. I had in mind to slowly increase the FSB to 400 MHz and match the new memory.
Reset back all OC to stock and start increasing the FSB by step of 5 MHz starting at 266 MHz.

Suddenlly, the computer did not boot, no post.
I try a very long reset, remove the battery. I try to boot with floppy to recovery the bios, but cannot load the floppy!!!

Is it dead?
Can I ship my first mobo somewhere to fix that problem?