Newer external hard drives are USB 3.0 compatible, with eSATA slowly disappearing from the market. Still, the eSATA port isn't used for many devices and doesn't seem to have much of a future to it. Of course, the eSATA port offers faster transfer rates than USB 2.0, useful for transferring large files like when backing up data onto an external hard drive. It's disappointing that no USB 3.0 port is on board. Along the front we also find an SD card reader. At the back toward the right we find an HDMI port and a Kensington Lock slot. After that come two USB 2.0 ports and a combined USB/eSATA port. Around the corner at the back, we continue with an RJ45 Ethernet port and the power connector.ДЄt the right toward the front, we have a 45mm Expresscard slot and underneath it the DVD drive. On the left side toward the front, we find the Smartcard Slot followed by an exhaust vent, a combination headphone/microphone jack, a VGA port and a USB 2.0 Port. Particularly the placement of the ports jumps out at you when you first look at the laptop, which are found around the back corners. Now we get to the selection and placement of ports on the E6420. The Lenovo T420 is the thinnest of the three at 30mm when closed (E64p both 32mm - all figures based on info from the manufacturers). The same is true for case depth: the front of the E6420 juts out about 10 mm when placed side-by-side with its rivals. The Lenovo T420 is 12 mm less wide and the HP 8640p 14 mm. In terms of case dimensions, E6420 is the widest at 352 mm. The particular configuration we reviewed included a 9-cell battery (97Wh), bringing the grand total up to 2.620 Kg. HP's model with the smallest possible 3-cell battery comes to 2.07kg, the same as the Dell E6420 with a 4-cell battery. The standard model of Lenovo's T420 weighs in at 2.24kg, that is, with a 6-cell battery included. Taking another look at the competition (Lenovo T420, HP 8460p), we see that the other contenders for your money also weigh a similar amount. The fans and heat sinks, the processor, memory, PCI module and the CMOS battery are all ready to be tinkered with once the cover is off. The rest of the hardware can be accessed by removing a cover along the bottom of the base unit which is fastened with a few more screws. The hard drive is secured by four screws, after removing which it can slide out from the case sideways. Repairing or switching out hardware is quite easy. Instead, they've gone with a long rubber strip encompassing the entire screen, which should serve to protect the screen and keyboard from dust particles getting in when the laptop's closed. Like HP, Dell is stepping away from the approach of sticking individual rubber pads along the display to soften closing. The display lid takes a bit of effort to tilt back but barely bobs back and forth after being adjusted. According to Dell, the display lid hinges are composed of tough steel, which is however not visible on the surface-as is the case with Lenovo Thinkpads-but is rather covered up a by a layer of magnesium. This includes the display lid that won't budge even a millimeter under pressure. This will cause the laptop to appear like the AC adapter is bad when the laptop is just not making connection with power.Our attempts to dent the surface had no effect whatsoever. Also, check the DC Jack on the back of the laptop to make sure it is not loose. Less than the required amperage will cause the power supply to burn up because the laptop is pulling more amperage than the AC adater can give it. It is also safe to have a higher amperage than marked on the laptop becuase the laptop can only pull the amperage it needs. AC adapters are safe to use within +/- 1V of the laptop voltage. It can be on the label on the bottom of the laptop or in the battery compartment. You should find a rating that looks like this: 19.5V - 6.65A. The rating should be taken from the laptop, not the AC adapter because this is the best match of what the laptop needs. Some models have more than one AC adapter depending on the amperage rating. When ordering a Dell Latitude E6420 AC adapter, check the voltage and amperage on the bottom of the laptop to make sure you are ordering the correct AC adapter. Read more about Dell Latitude E6420 AC Adapters before ordering

Dell latitude e6420 power supply