The cover plate with the Micron logo and branding is not user-removable. The cover is applied with adhesive backing that will likely strip the 48 Tantalum capacitors from the PCB upon removal. The center of the faceplate, which covers the heatsink, also has a thermal pad for conducting heat to the cover of the P420m, in essence creating a large metal heatsink with the cover.
The Tantalum capacitors provide enough capacitance to flush data in-flight down to the NAND in the event of a power loss. We note the spare pads for the possible inclusion of more capacitors, perhaps signaling a higher capacity version of the card in the future.
Looking at the P420m from the edge reveals a triple-stacked PCB architecture. The heat sink isn't exposed to an abundance of air down among the PCBs, perhaps explaining the thermal pad scheme on the cover. We closely monitored the temperature under heavy loads and the P420m remained within expectations.
Ten very thin copper strands connect the top PCB with its capacitors to the bottom PCB, which holds the controller.
Upon removal, we flip over the top PCB, which holds the capacitors, and not the traces that route the capacitors to the 10-pin connector.
Both pictures above detail the middle PCB, which holds the lion's share of the NAND. The 25nm Micron MLC NAND packages total 36 for this component. Each package contains 32GB of NAND, with eight die per BGA package. The 700GB P420m has the same number of overall NAND packages, but contains only four die per package.
The bottom PCB contains the Micron/IDT ASIC, a 32-channel beast that provides native PCIe to the 2.0 x8 connection. The remainders of the NAND packages reside on this PCB, along with several DRAM packages hidden under the secondary heat sink.
Finally, the bottom of the main PCB holds the remainder of the ECC DRAM, for a total of 2.25GB. The use of ECC RAM allows for the detection and correction of any areas in the cache. We also note the remaining NAND packages crammed into the scant space available on the PCB.