A Guided Tour Of SanDisk's Extreme II
Taking the Extreme II apart is easy. Four screws hide behind the label, and the plastic top half falls away from the metal chassis down below. A series of thermal pads mate PCB components to the metal housing for improved heat transfer. These pads cover the DRAM cache, Marvell's controller, and the eight NAND packages. It's like silly putty in a way; it tends to pull the screen printing off of component ICs, making them harder to decipher in photographs.
The 240 GB PCB you see here may not completely reflect the final product. What shouldn't change, however, are the eight quad-die packages of 19 nm ABL eX2 Toggle-mode NAND, adding up to 256 GB of capacity. The Toggle-mode interface eliminates the clock signal needed by synchronous flash, theoretically lowering power consumption. We've seen similar power characteristics from the 19 nm flash manufactured by Toshiba and SanDisk, though older Toggle-mode-based SSDs tended to use more power than competing drives with ONFi-compliant memory.
Marvell's '9187 controller is flanked by 256 MB of Hynix DDR3 DRAM. We like to see a ratio of DRAM to NAND running 1 MB for every gigabyte of flash on-board, so it makes sense that this 240 GB Extreme II has 256 GB riding shotgun. The 120 GB hosts 128 MB of cache, while the 480 GB model sports 512 MB.
The PCB's back side is bare, aside from some solder points.
