Re: CPU and RAM questions.
The xeon processor is slightly faster at stock than the 980x.
The main difference, however, is that the 980x has an unlocked multiplier, which means it's MUCH easier to overclock it.
If you had to get one, I'd go with a 980x and OC it.
As to the ram question, technically the i7's can only officially support 1066Mhz ram, but unofficially they can run ram as high as 2000Mhz, even higher in some cases.
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