4 sticks does thin out the voltage, but this usually isn't a noticeable issue. I've never used super high clocked RAM before for various reasons, but i think i can see why it would have issues if 2 kits of 2 were being used to arrive at the 4 sticks - the programmed XMP settings could be wrong since they were designed for a pair, not 4. Usually not an issue, but i can see how not only voltages but also timings would become very touchy at 3200mhz.

Or maybe there's simply a bad RAM slot?