Choose second-hand hard disk carefully, don't be greedy for petty gain, because hard disks are generally maintenance-free products, and hard disks are damaged, especially internal damage, which is difficult to repair. If the hard disk has a bad track, it can't be seen from the surface. If you buy such a hard disk, it won't be long before the bad sectors get bigger and bigger. In addition, pay attention to see if the hard disk has been repaired. Look at the back of the hard drive carefully. If you see the letter "R" after a row of dates, then the date marked is the date of hard disk maintenance, not the date of hard disk production; And if you see the word "repaired" (English means "refurbished"), it goes without saying that this must be a repaired hard disk. Most importantly, when buying a second-hand hard disk, it is best to re-partition and format it in front of the merchants. If all goes well, it proves that the hard disk can still be used.
2. Motherboard and graphics card
Buy second-hand motherboard and graphics card and other board accessories, first look at the solder joints behind. If there are traces of new welding or some solder joints are obviously different from the surrounding areas and look rough, it can basically be concluded that they have been repaired. Check the capacitor on the front of the circuit board again for damage. If you find a capacitor bulge, don't buy it. Although you use it now, there is no guarantee that it will not go wrong after a long time. In addition, if you see several layers of labels on the board, and the dates are different, some dates are far from other dates, you should also be alert, and maybe they are repaired.
In fact, the maintenance technology of this kind of board is very demanding, and there is no professional maintenance equipment in general places. Most people just treat headaches and foot pains. A chip burned out, but it's actually easy to repair. But why is it broken? What caused it? Will the same problem happen in the future? Used computers sellers don't care at all, and they won't try to solve these problems.
3. Monitor
For second-hand monitors, the author does not intend to say more here. For example, in the past, many monitors in my unit had some problems, such as unable to open, color cast and blurred display. I have had it repaired. The maintenance staff said that these monitors can be used for up to one year after repair, and they should be basically scrapped after one year, and there is no value in repairing them. More than half a year later, those monitors did have problems one by one.
Some second-hand monitors sold in the market look very new, but they are actually sprayed with a new layer of paint, but the life of the monitors will not be extended. The new appearance is just a psychological comfort. If you buy such a monitor, you might as well buy a new one, which can also protect your health.
4. Optical drive
CD-ROM drives are frequently used and have a short service life. Considering that the accessories in the second-hand market often bump, this makes the original fragile second-hand CD-ROM more vulnerable to damage. Therefore, if you want to pick out the satisfactory optical drive in the second-hand market, you have to work hard.
The choice of second-hand optical drive is divided into two steps. The first step is to look at the appearance of the CD-ROM drive. This step is no different from identifying other hardware, only looking at some superficial problems such as label, production date and wear degree. These can only give you a little inference, but can't judge the quality of this CD-ROM drive. At most, you can open the tray to see if there are any signs of damage or disassembly of the parts inside. In contrast, the second step is particularly important, which is relatively easy to operate. Prepare a worn-out CD by yourself. When you choose a second-hand CD-ROM drive, try it in and see how it reads and corrects errors. If it is a burner, you can also try its erasing function on the spot. Try not to have any problems, and this CD-ROM drive will not have any big problems.
5. Floppy disk drive
It's easy to buy a second-hand floppy drive and you don't need any special professional skills. Just try a floppy disk. You can read and write. If you try to read the disk format on the spot and copy and delete the file smoothly, there is definitely no big problem, so you can choose with confidence. Its disk reading effect and life span may be better than many new floppy drives.
6.CPU and memory
Pay attention to whether there is polishing when buying CPU. If it is not polished, check whether its nominal frequency is consistent with the frequency displayed at startup. If not, it means that the merchant has overclocked the CPU. Of course, if conditions permit, it is best to find an expert present to prevent any mistakes and misfortunes, at least to give the profiteers some shock.
Pay attention to this when buying memory, and see if the merchants will polish the memory chips with lower frequency and then re-paste the products with higher frequency for sale. The method of identification is also very simple. Taking a photo of the memory particles under the lamp can clearly see the traces of polishing, because the surface of the polished memory particles is fuzzy, dim and rough to the touch. Please be careful in the purchase process. In addition, don't miss the golden finger, look at the thickness first, and then look at the degree of wear. If both are poor, then consider it, because it is likely to be in poor contact. Generally speaking, the condition of second-hand memory is generally not optimistic because of the frequent plugging and unplugging, so pay attention to more selection when buying.
7. Chassis
When buying a second-hand chassis, first remove the side plate of the chassis and hold the chassis diagonally with both hands to see if it is deformed; Then look at the thickness of the steel plate used in the case shell and the thickness of the support steel plate used for bearing in the case; In addition, let's see if there are any cuts in hidden places. I have seen some inferior shells before, and there is nothing in front except a plastic shell, which can't shield electromagnetic radiation at all. It is also a good choice if you can find some second-hand chassis of brand machines in the market. Because the chassis of most brand machines is still good.
8. Power supply
When buying a second-hand power supply, you can weigh the power supply first. It's definitely not a good power supply. You can cut corners. Then see if it has any signs of disassembly, and then look inside through the cooling hole. If there is a lot of dust in it, the power supply must have been used for a long time. Dial the power fan with your finger again. Some power supplies have been used for too long, and the fans have stopped working. The consequences of such a power supply can be imagined. Finally, don't forget to look at the actual power of the power supply. Never judge the rated power of a power supply according to its model. It is best to judge according to the maximum current of each output of the power supply. The greater the output current, the greater the rated power. Generally, the maximum output current of +5V is multiplied by 10 to judge the rated output power of the power supply.