G.Skill didn't just make a splash in the memory market by announcing its new RipjawsZ! Extreme Performance quad-channel memory line, it emptied the entire pool by rolling a 64GB cannon ball into X79 waters. The RipjawsZ! are specifically intended for Sandy Bridge-E systems, and if you're stepping up to the 64GB kit, you'll need a motherboard that's able to handle eight 8GB memory sticks.
The 64GB kit is clocked at 2133MHz with timings tuned to 11-11-11-30 at 1.5V. If that's too excessive -- and for most people, 'excessive' is putting it lightly -- there are also 32GB (8GBx4, 2400MHz, 1.65V) and 16GB (4GBx4, 2500MHz) kits available.
All RipjawsZ! kits are XMP 1.3 ready and supposedly "hand-tested in a range of X79 motherboards according to G.Skill's rigorous qualification procedure."