What BIOS version are you using? The newest F5 BIOS added support for for the X6's. If you haven't already, get it from the Gigabyte site and update it. Read from page 66 of the motherboard manual on how to do so. Hopefully, that will solve your problem.
I upgraded to the F5 version. No change.
The Corsair memory that I'm running is 1.5v, but this mobo can only go down to 1.6v.
Gigabyte now says that this memory is not on their Qualified Vendors List http://www.gigabyte.fr/FileList/MemorySupport/mb_memory... .
I bought this as a kit from TigerDirect/CompUSA. So far they have been useless, stating only that they are removing this barebones system from their website.
I ended up having to RMA the memory.
I replaced it with Patriot and the mobo now boots and restarts with no beeps.
Too bad CompUSA/TigerDirect doesnt check for compatibility before they bundle a package.