Samsung 840 – 250GB SSD Review

A closer look at the Samsung 840 hardware.

Let’s take a look at the hardware found inside the Samsung
840 SSD.

At this point I would normally open up the drive and take
some screenshots of the components found inside. Unfortunately this was not
possible with the Samsung 840. The screws holding the drive together have tiny
hex type heads, and I didn’t have a tool small enough to fit the screw heads.

However, I can write some text about the components.


The SSD controller

The SSD controller is the new Samsung MDX. This controller
is based on an ARM Cortex R4 and has three cores, with a clock frequency of
300MHz. The MDX controller also supports an AES-256 encryption engine, by means
of password protection in the system UEFI/BIOS.

The firmware onboard the review sample is DXT07B0Q, which is
the latest production firmware.


The NAND is Samsung’s own SSD grade 21nm toggle DDR2 TLC
NAND, with 400Mbps bandwidth per die.

MLC NAND as we know stores 2 bits of data per cell, meaning
that each cell has four possible states, which all require a different voltage
to access one of these states. The four possible states for MLC NAND are as

  • 00 (high voltage)
  • 01 (medium high voltage)
  • 10 (medium low voltage)
  • 11 (low voltage)

From this you may expect TLC NAND to have six possible
states, but this isn’t so. TLC NAND has eight possible states, and requires
eight different voltages to access, erase, and program the NAND, which makes
TLC much more difficult to program. The eight possible states for TLC NAND are
as follows.

  • 000 (highest voltage)
  • 001 (high voltage)
  • 010 (medium high voltage)
  • 100 (high medium voltage)
  • 011 (low medium voltage)
  • 101 (medium low voltage)
  • 110 (low voltage)
  • 111 (lowest voltage)

With all these different states and voltages required, not
only is TLC more complex, it is also less durable, and it takes longer to erase
the NAND as well.

The cache

There is 512MB of LPDDR2 (Low power DDR2) onboard the 840,
which is clocked at 1066MHz, and once again manufactured by Samsung.


I found the following specifications at Samsung’s website.

Samsung 840 - 250GB SSD Review

Samsung 840 - 250GB SSD Review


Drive maintenance features

For Windows 7 and Windows 8 users and some distributions of
Linux, the Samsung 840 series SSD supports ATA TRIM to keep the NAND clean. The
Samsung 840 series also has advanced garbage collection to clean the NAND
during drive idle periods.

Samsung 840 - 250GB SSD Review
Samsung SSD Magician

The SSD Magician software allows the user to maintain the
SSD, and has the following features.

  • Disk drive: Brings up useful information about the
    SSD, including its health status and how much data has been written to the
  • System info: Allows the user to see system and
    drive properties.
  • Performance Benchmark: Performs a very basic
    benchmark on the SSD.
  • Performance optimization: Performs a manual TRIM of
    the SSD.
  • OS Optimization: Allows operating system features that
    can affect SSD performance, to be switched on or off.
  • Firmware Update: Allows the Samsung 840 firmware to
    be updated.
  • Secure Erase: Sends a Secure Erase command to the
    SSD, clearing all NAND and returning the SSD back to its default factory
  • Over Provisioning: Allows the user to set aside a
    given amount of NAND as a manual over provisioning area.
  • SSD authenticity test: Checks to make sure
    that the SSD is a genuine Samsung SSD.

Samsung 840 - 250GB SSD Review
Performance benchmark


Samsung 840 - 250GB SSD Review
SSD authenticity test

Samsung 840 - 250GB SSD Review
Over-provisioning utility


Let’s head to the next page where we take a look at our
testing methods and the review PC.