1. VDIMM has to be within 0.5v of Uncore voltage (refered to on some boards as QPI/PLL volts or CPU VTT) for CPU to be safe above >1.65v DRAM memory voltages True

2. CPU VTT max 1.375v spec'd some have benched 1.55v so gives VDIMM a 1.875-2.05v range FALSE
3. UNCORE (CPUZ NB frequency) needs to optimally be twice that of MEM frequency TRUE
4. SOMETIMES for stability, having VCORE within 0.02-0.03v of CPU VTT might stabilise things Way FALSE
5. Yes, theoretical QPI frequency limit is around 4000Mhz but it's too early to say if we can surpass that, some boards and cpu combinations possible could in future. Way TRUE