CPU VDD is the voltage regulator of the CPU-V
CPU V is the voltage of the CPU itslef
CPU-NB VDD same idea as the CPU VDD, but for the CPU-NB
CPU-NBv is the voltage for the CPU-NB
CPU PLL voltage is something i've never heard of.
So here is the run down: Voltage comes in from the PSU, and then goes to mosfets, and then to the CPU and CPU-NB. The Mosfets can be regulated to send X amount of voltage to the CPU and CPU-NB, this can be further controlled by the VDD, which is bascially your head room.
Or stated by Bit-Tech for refrence:
CPU Vdd Voltage: This is the positive voltage supplied to the FETs.
MSI states (on another 790FX board with Phenom II) that 1.3 to 1.4V is typical safe value, however we've increased it here because we've added additional cooling to the CPU socket area with two large fans.
CPU-NB Vdd Voltage: This can also help with increasing the integrated memory controller overclock - we've not increased it here, but considering AMD claims 1.4 to 1.5V for the CPU-NB core for optimum results, the CPU-NB Vdd should also be ~1.3 to 1.4V.
CPU Voltage: Typically the 45nm SOI Phenom IIs can withstand quite high voltages so 1.5V should be OK if it's properly cooled. However it's worth mentioning that this is wrongly labeled, and is actually the voltage offset, as increasing the Vdd above adjusts this value as well.
CPU-NB Voltage: Like the above setting, working in combination with the CPU-NB Vdd setting will give you an additional voltage. Work with mostly Vdd and start with a small setting here.
CPU PLL Voltage: Similar/same as the VDDA on Asus boards and can directly reflect chipset and MOSFET temperatures so it's worth keeping an eye on the heatsink. 2.6 to 2.8V can sometimes make a difference: MSI allows particularly fine tuning on the GD70, but we found it didn't affect our overclock so we left it at the cooler 2.65V.
http://www.bit-tech.net/hardware/cpus/2009/05/11/overclocking-amd-s-phenom-ii-x3-720-be/3