First, the settings problems associated with the system installation
1. Do not think that as long as the motherboard has USB interface, you can use removable hard disk, depends on whether the system supports. Windows2000, WindowsXP and above versions of the system can directly support external hard disk, and not need to install the driver to use, while in Windows98 to use external hard disk must be installed with the driver, or the system will be external hard disk identified as “unknown USB Device. ”
2. For some Windows98 users, the external hard disk installed the driver, you can see the external hard disk icon from the Device Manager, but the Explorer does not include the corresponding letter symbol, and this is the system set up properly result. In the Device Manager, double-click the Hard Drive icon, and click the pop-up window in the “Properties” button, and you could see the “disconnect”, “can delete”, “Sync data transfer” and “INT 13 unit” 4 options, which “can delete” a previous system default is no tick, and check this option, restart your computer, you can see the new external hard disk drive letter in the Explorer.

Second, the motherboard USB interface issues
As the motherboard USB port problems caused external hard disk is not working, mainly from the following address:
1.USB interface is not open: in some old machines (including some branded machines) Although there are external USB interface, but it is off by default in BIOS, so even if the system supports is not OK, it should check the BIOS settings USB interface option is open: When you start your computer holding down the Del key to enter BIOS settings, in the “Chipset Features Setup” or “Integrated Peripherals” will “OnChip USB” is set to “Enabled”, save and reboot the computer.
2. The system does not support the USB interface: This also was seen in some old computer. As the author of this platform compatible, motherboard is the flagship of the VISTA710V2, motherboard chipset, using a VIA Apollo MVP3, external USB interface card system could not recognize (the installed Windows Me and Windows 2000 dual-boot), in the “Device Management device “not found in” Universal Serial Bus controllers. ” Internet an investigation, the original problem is the motherboard chipset, and quickly downloaded from the Internet for the latest motherboard BIOS update, then downloaded the VIA chipset available exclusively for the USB driver patch, my computer finally recognized the “Removable Storage equipment. ”
3.USB interface, insufficient power supply: the vast majority of external hard disk work required to 5V Voltage, 0.5A current can be directly through the motherboard’s USB port supply, but some USB-powered board not reach this value, thus external hard disk can not be led to the system identification. Fortunately, a dedicated HDD enclosure USB connection line, a majority of separation of PS / 2 connectors, so long as the connector plug in the motherboard’s PS / 2 interface, it will be ok.

Third, improper operation led to the external hard disk can not be used
Due to improper operation caused by external hard disk is not working, mainly refers to the plug external hard disk is not the time to master.

1. Before docking external hard disk, you should shut down the running applications, and do not plug in the system startup process.

2. There will be a process to read and recognize external hard disk when it has just connected to the system, it is best not to carry out any operations before the end of this process (recommendations to divide less partition, sub-district the more, the system identification plate longer), you have to wait until external hard disk light stabilized.

3. The mobile hard drives will appear the situation that it can be used before, but occasionally can not be used, first delete “Unknown USB Device” in the “System Device”, and then unplug the external hard disk, and then reboot the system, and then connected it, the fault can be solved in general.

4, External hard disk its own problems

If the failure exclude the above reasons, the external hard disk still can not use, it is very likely to be external hard disk itself has a problem. Mobile hard drives are relatively simple structure, mainly by the disk drive casing and the composition of notebook computer hard drives, hard disk box is not easy in general bad, problems are mostly caused by laptop hard drive. External hard disk itself in order to avoid hardware damage, you should pay attention to the following aspects:

1. The use of external hard disk should be placed on a stable place, do not move and make it shaken when it read and write.

2. When you unplug and move the hard disk, you should in strict accordance with procedures: such as the hard disk does not read the disk, double-click the task bar bottom right corner of the “unplug or eject hardware” icon, first “stop” the use of equipment in the window that appears, and then remove the device from the system option, the last unplug the HDD from the computer (can not unplug the hard disk when it read and write, otherwise it’s easily damaged laptop hard drive).

3. Even in the non-work state, vibration is also the biggest killer of external hard disk, which requires users to take effective damping measures when carry out external hard disk (some brands of external hard disk is doing better, the equipment itself has taken the anti-shock measures), it is best put it in a box surrounded by plastic foam.

Eaget Hard Drive H100 (250G)

Eaget Hard Drive H100 (250GB) parameters:
Model H100 (250G)
Device Type Hard Drive
Capacity Size 250G
3.5-inch hard disk type
7200 RPM hard drive
The main parameters embedded SATA perpendicular recording technology, with 8MB cache technology, using the United States imported chips and FDB automatic hydraulic roller-balancing technology wireless suspension GMR head design, using high-density aluminum-magnesium alloy casing design can be compressive, impact and anti-corrosion, can be applied to store backup files, movies, music, pictures, software, data, files, etc.
Interface USB 2.0 port, DC in port
Size 178 × 106 × 28mm
Annex (gift) USB 2.0 cable, power cord, user manual and warranty card, certificate, drivers, exquisite packaging
Other parameters to support Win98/ME/2000/XP, Mac OS 8.6 and Linux 2.4 or higher version of the system, national service, one year warranty, silver exterior color and black, presented special EA_key2.0 encryption tools and antivirus software Genuine Jinshan (one-year free upgrade)

Patriot external Hard Drive

Patriot External Hard Drive – Features Storage King H8176 (320G)
Model Features Storage King H8176 (320G)
Device Type Hard Drive
Capacity Size 320G
2.5-inch hard disk type
5400 RPM hard drive
The main parameters patented three-dimensional dynamic shock absorption
Patriot Masters can be installed to achieve encryption security
Interface USB 2.0 interface
Other parameters blue and white porcelain products, mirror the appearance of blue and white silk screen design

(1) best not to use the USB extension cable, the quality of this line was not very good, leading USB data synchronization make mistakes, and does not work properly. If the chassis on the front USB port can not guarantee normal use, mostly is the power supply problem, you should insert it on the USB interface of the original motherboard backplane.

  (2) low-quality USB HDD enclosure working poor, resulting in insufficient supply of electricity, or loss of data and so on. May try to replace the bad data line with a high quality USB cable with a shield; if the situation remains, you could borrow or swap a hard drive to test; if not solved the problem, the most reliable solution is to replace the external hard disk box as soon as possible.

(3) The compatibility of USB interface is poor; now the situation has been relatively rare but still not ruled out.

There are a variety of external hard disks, according to volume; it can be divided into 3.5-inch external hard disk, 2.5-inch external hard disk, as well as 1.8-inch external hard disk. Of which 3.5-inch are bulky and need to connect an external power supply, portable is poor; 1.8-inch have small size and low consumption, small capacity, Unfortunately, poor performance and the price is slightly higher, compared with the U disk, it have no advantage, resulted in 1.8-inch external hard disk slow development of embarrassment recent years. The remaining 2.5-inch positioned between the former two types of external hard disk, and it is the mainstream external hard disk type.

According to brands, external hard disk can be divided into three types: original, brand and DIY, original means that the hard drive are offered from the major manufacturers, such as Hitachi NESO, Western Digital and Maxtor, etc.; Brand External Hard reality is those built-in other brand products, like Yi Jie, BenQ, Li Jie, etc; DIY means fabricated the hard drive purchased separately together with the hard case.

Consumers went to purchase external hard drives often do not know which type he should choose. If the budget is adequate, the best choice is original external hard disk, these drives are not only stable, value-added feature-rich, and often have a better shape, of course, brand also has this advantage, it’s more benefits than the original external Hard, but it’s better to select a good brands when purchasing, not to fall into the trap of external hard disk cottage. However, the DIY have a high cost-effective, if you have less budget, it’s an excellent choice, it could help you get a greater capacity, so it’s more popular with students.

1. Capacity.

The capacity of external hard disk is generally between 4.7GB ~ 40GB On the market, 4.7GB ~ 20GB is enough for normal use, because the external hard disk only is a transitional storage medium, there is no need to use much capacity. However, as the hard disk capacity and price is not proportional, high-capacity tend to have more cost-effective, and most of it less than 20GB is already eliminated, it is proposed that it’s better select it more than 20GB when you buy a new external hard disk, but if you buy hard drive box back and assembly it, that is another matter.

    2. Size.

 External hard disk composed of drive and hard disk boxes, the latter including the interface and control circuitry. There are usually two  size: 2.5 inch and 3.5-inch, corresponding to notebook and desktop computer hard drive. The size of 2.5-inch hard drive and the weight is smaller, more portable, but the price expensive than the 3.5-inch hard drive. Generally recommend selecting the 2.5-inch hard drive.

   3. Interface.

External hard disk is generally used USB interface (IDE interface has also been used early, but it’s inconvenient, you should open the case to connect it), you should pay attention to USB interface, it has two kinds of specifications: USB1.1 and USB2.0, the latter’s speed of data transmission faster than the earlier ones hundreds of times, basically have the same speed of exchange data with built-in hard drive, but the price is a little expensive. External hard disk with USB2.0 interface is the first choice.

   4. Purchase of finished goods or DIY.

You can select finished goods and used it directly when purchased external hard disk, but can also buy a suitable external hard disk box (which is not contain the hard disk, it contains the appropriate USB driver circuit and interface circuit, USB transfer cable, as well as an external power supply) in the computer market, then with 2.5-inch notebook hard drive, DIY your own USB external hard disk. HDD enclosure accompanied by an old laptop hard disk, the cost-effective entire external hard drives are higher.

You should pay attention to the distinction between size and interface specification when purchasing external hard disk box, and you can refer to the above description.

The attention of the problems when using external hard disk

(1).External hard drive connections:

USB connection cable of external hard disk is not only data transmission lines, but also it’s power lines, connection is too long will increase resistance and data interference, caused external hard disk does not work, so pay attention to: USB transfer cable as short as possible, in addition to the original connecting lines, should not be connected to extend line; second, you should choose  the USB interface (fixed directly on the motherboard interface) which behind the chassis, don’t use the front interface (which are connected by the board after a period leads to the front panel) of the chassis.

(2) External power supply of external hard drive:

The power of hard drives and data interfaces offered by computer’s USB interface when it working. However, when using external hard drive more than 10GB, relying solely on USB cable to offer power to the hard drive may be led to it not working properly due to electricity shortages, at this time it is necessary to use an external auxiliary power supply (DC power).

(3) Although external hard disk used USB interface, and support hot-swappable, but there is something you should pay attention to during use (Windows Me/2000/XP system): you must ensure that you have closed USB interface when unplugging the USB connections (mouse click on the date next to the USB interface sign, close interface), otherwise, a power outage may cause the hard disk drive damage when it in a high-speed operation!

1, Setting the CMOS parameters

If you never used the USB external device, there may occur the case: the system can not detect USB hard drive even if the driver is properly installed, which was mainly due to the motherboard CMOS default port is closed, if not set to open state, it naturally Windows can not detect the external hard drive. In order to solve this problem, we can re-boot into the CMOS settings, and set “Assign IRQ For USB” to “Enable” in “PNP / PCI CONFIGURATION” column, now the system can be assigned to the USB port available interrupt address.

2, Power shortage

As the USB drive need to consume some power when it at work, if directly through the USB interface to take power, the power supply may be not enough. Thus, almost all of the external hard drive comes with a separate external power supply or a PS2 keyboard to take power transfer interface, at this time you should connect external power supply or through the transfer cable ps2 connected to keyboard to ensure that it have provided adequate power to the external hard disk, recommended that you should ensure the external hard drive have adequate power supply when you use it, otherwise, the external hard disk is likely to be damaged due to insufficient power supply.

3, USB extension cable fault

USB interface type does not match the external hard disk interface ,this case caused it can not be used. For example the standard USB interface of the computer configuration is 1.1, while the external hard drives purchased are USB 2.0, which requires the cable connected computers and external hard disk must support USB 2.0 standard. Because high-speed mobile device plug in a low-speed hub, the device may not be properly installed, and some people use external hard disk while using USB flash drives, For convenience, they directly used USB 1.1 standard cable that supplied by USB flash drives, as a result, the USB 2.0 standard hard drive not be recognized correctly. Just replace  it by the USB 2.0 standard cable can solve this problem.

4, Windows version is too low

Pre-Windows 98 operating system does not support USB peripherals, so in any case to install the driver, set the CMOS parameters are unable to make normal use of external hard disk. In this case, one solution is to upgrade the operating system up to Windows 98, another way is to Microsoft’s official site, download the appropriate patch to make it can identify mobile hard disk.

5, The system is set incorrectly

When installed driver, the external hard disk icon will be seen on the Device Manager for some Windows 98 users, but the Explorer does not include the corresponding letter identification, which is improper system settings. In the Device Manager, double-click the Hard Drive icon, and click the pop-up window in the “Properties” button, and you could see disconnect, could be deleted, synchronous data transmission and Int 13 unit four options, of which “could be deleted ” is no tick in front of the system, and simply check this option to restart your computer, you can see in the Explorer, the new external hard disk drive letter.

While the failure of the external hard disk does not recognized are more the reasons, but generally not the USB interface or external hard disk’s own fault, so it requiring us to consider some more from around the association when exclude it, I believe you can successfully use the external hard disk.