Figure 2. Thickness differenceCurved edgeDDR4 modules feature a curved edge to help with insertion and alleviate stress on the PCB during memory installation.Figure 3. Curved edgeMemory ErrorsMemory errors on the system display the new ON-FLASH-FLASH or ON-FLASH-ON failure code. If all memory fails, the LCD does notturn on. Troubleshoot for possible memory failure by trying known good memory modules in the memory connectors on the bottom of thesystem or under the keyboard, as in some portable systems.USB featuresUniversal Serial Bus, or USB, was introduced in 1996. It dramatically simplified the connection between host computers and peripheraldevices like mice, keyboards, external drivers, and printers.Let's take a quick look on the USB evolution referencing to the table below.Table 19. USB evolutionType Data Transfer Rate Category Introduction YearUSB 3.0/USB 3.1 Gen 1 5 Gbps Super Speed 2010USB 2.0 480 Mbps High Speed 2000USB 3.0/USB 3.1 Gen 1 (SuperSpeed USB)For years, the USB 2.0 has been firmly entrenched as the de facto interface standard in the PC world with about 6 billion devices sold, andyet the need for more speed grows by ever faster computing hardware and ever greater bandwidth demands. The USB 3.0/USB 3.1 Gen 1finally has the answer to the consumers' demands with a theoretically 10 times faster than its predecessor. In a nutshell, USB 3.1 Gen 1features are as follows:• Higher transfer rates (up to 5 Gbps)Technology and components 71