Nowadays, the USB3.0 data interface is becoming more and more popular, and the newly launched notebooks will basically have multiple USB3.0 ports. Even the new motherboards such as the B75 and Z77 for the new generation of IVY processors are compared to the SNB platform. The big difference between the motherboards is that the B75, Z77 and other motherboards have newly added USB3.0 high-speed interfaces. Let's talk about USB3.0 together.
According to the media, the transmission speed of USB 3.0 is 4.8Gbps, which is ten times that of USB 2.0. Yes, it is a G-class, but this is a bit (bit), not a byte (Byte). Just like if you pull a 4Mbps network cable, the actual download speed can only reach 512KB/S. Because 8 bits = 1 byte, that is, 4.8Gbps = 600MB/S, this is still the theoretical value of 600MB/S, which is really fast. But to achieve this speed, we must break through these two bottlenecks: motherboard interface, storage medium. You rushed to the computer city and bought a USB 3.0 mobile hard drive to try it out, and found that it was still at the speed of USB 2.0. The bottleneck is probably the motherboard interface. Although various manufacturers have launched USB 3.0 motherboards, because Intel has not integrated USB 3.0 host controllers in its chipsets, USB 3.0 motherboards have not yet become popular and are relatively expensive. The so-called USB 3.0 motherboards you see now are transitional products. Most of them bridge two blue USB 3.0 ports through a third-party USB 3.0 master chip. PS: If your desktop motherboard does not have a USB 3.0 interface, but there are still free PCI-E slots, you only need to buy a PCI-E to USB 3.0 adapter card; for laptops, buy a PCMCIA to USB 3.0 expansion card (USB 3.0 ExpressCard) will do. This kind of card sells for about 70 yuan, and the D720200F1 is still used.
Even if there is a USB 3.0 interface from the motherboard, the mobile hard disk used is also USB 3.0. Can the actual transfer speed reach 600MB/S? I can tell you with certainty: there is no drama at the moment! Limited by the mechanical structure of the hard disk, the internal transfer speed of the mainstream 3.5-inch 7200 rpm 500G hard disk will not exceed 150MB/S, and the internal transfer speed of the 2.5-inch 5400 rpm 500G mobile hard disk is lower. I used a 120G mobile hard drive equipped with USB 3.0 interface to test on a host equipped with Gigabyte G41 motherboard, Pentium E5800 CPU, DDR3 1333 2G memory, and USB 3.0 Express Card. ATTO showed that the read and write speeds only reached 45MB. /S and 47MB/S (the bottleneck has appeared in the hard disk, which is the transfer speed of the hard disk). Of course, people with rice can buy an SSD solid state drive to try, and the speed will be much faster (the new SSD has a read and write speed of 500MB/S).
The USB 3.0 interface, for some devices, is just a gimmick by the merchants. For example, USB 3.0 keyboard and mouse, compared with USB 2.0, is there any difference? Yes, but it is meaningless, because the amount of data that the keyboard and mouse need to transfer is very small, and USB 2.0 is more than enough.
For USB 3.0 flash drives, the speed bottleneck lies in the main control and FLASH chips used. Some time ago, Zhao Steak went to Huaqiangbei to see a top-quality U disk with a write speed of 96MB/S and a read speed of 110MB/S. The silver-can master control was used, and the FLASH seemed to be a Samsung or Magnesium SLC (both longevity and speed). higher than ordinary MLC). At that time, I was thinking, if that notebook uses SSD, will the actual transfer speed of this U be faster?
The USB 3.0 card reader is similar to the main control + FLASH of a USB flash drive, but this FLASH exists in the form of "plug-in". The actual transfer speed depends more on the memory card itself, and different memory cards have very different speeds. The common cards on the market are cards with a write speed of only a few MB to a dozen MB.
Putting aside the bottleneck problem, the transfer rate of the USB 3.0 interface depends on the size and number of files transferred, which is the same as USB 2.0. It is also 100M of data, and it is much faster to transfer a single file than hundreds of fragmented files. Anyway, USB 3.0 is a trend that offers the possibility of faster file transfers, although there are various speed bottlenecks at the moment.
The theoretical interface rate of USB 3.0 is 5Gbps, but it uses the 8/10b encoding method to encode 8-bit data into 10-bit data for transmission. Therefore, the theoretical data transfer rate of USB 3.0 is 5Gbps/10=500MB/s.
USB 2.0 does not use the 8/10b encoding method. Therefore, the theoretical interface rate of 480Mbps can be used to transmit data, that is, the theoretical data transmission rate of USB 2.0 is 480Mbps/8=60MB/s.
The transfer rate of USB 3.0 is 500/60=8.3 times higher than USB 2.0, not 10 times.
The enhanced power supply of USB 3.0 cannot be ignored. The same is 2.5 inches, and the power supply voltage is also 5V, but the current requirements of mobile hard drives are high and low. The maximum current supply capacity of the USB 2.0 port is only 500mA. When there is no external power supply, we often encounter the situation that some mobile hard disks with high power consumption cannot work. Even if they can barely work, it is not uncommon for the hard disk to be damaged. Sometimes connecting the mobile hard disk to the USB 2.0 port on the back panel can be used, but connecting to the front USB 2.0 port may not work (because the bad wire has a large voltage drop). USB 3.0 has improved the power output capability, each port is up to 900mA, and the combined output power is 4.5W, which can already meet the needs of most mobile hard drives.
In any case, the data transmission speed of usb3.0 has indeed been greatly improved compared to usb2.0. With the gradual popularity of USB3.0, USB3.0 will gradually replace the current USB2.0 in the future. Friends may wish to learn more about it.
