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#21
That's because you don't have a P55 chipset. You have an X58 chipset, the X58 number in your MB model
As for the memory you currently have - you can use it, but it's paired for a dual channel system, the the 4 module kit (4x2)
If you got/get a triple channel kit, it would be packaged in either a 3 or 6 module kit, either 3x2 or 6x2.
So.... if you want, you could just remove one of the modules and just run 6gig. Since the kit is matched anyway it shouldn't be a compatibility problem.
The issue is running an odd (odd as in RAM size) configuration - 8gig as opposed to either 6 or 12gig.
That "may" be what causing the odd issues, the way you have to configure (install) the RAM.
My two cents.
And it should. Don't do anything to it.