The motherboard is powered on but not bootable what's going on?

The motherboard is powered on but not bootable what's going on?

1, Power switch failure

When the power switch button because the aging can not be reset or chassis front panel because of the deformation caused by the power switch button can not be reset in time, using the switch is always in the state, then the power switch will appear after the main engine to start, but after 4 seconds automatically shutdown.

If the relevant line of the power switch appears short, when we connect the host power plug, the host will be powered up, 4 seconds after the automatic shutdown.

Check the method to unplug the board with the motherboard pw_on interface connected to the panel switch, directly with a small screwdriver short patch jumper, observe whether the host still 4 seconds shutdown failure. If the failure disappears, you can conclude that there is a problem with the switching circuit.

2, reset switch or jumper is shorted

Although this type of failure occurs, but with the increase in the use of computer time, the reset key use of the non-self-locking button switch will be due to the elastic failure of the press can not bounce, resulting in always connected state; or because the buttons on the front panel of the chassis are not installed or deformed, Cause reset switch button can not be reset in a timely manner, long time in the state; again, because of our overhaul process, pull, pull plug inadvertently caused reset line short connection. At this point, when we press the power switch, because the motherboard is always in the reset state, although the mains has been connected, the CPU fan and Power fan, video card fan, the motherboard fan has started to work, but the host does not have any boot traces.

If we have the debug card inserted into the PCI slot, we will immediately find that the reset light is always bright, you can immediately determine the power of the reset related to the phenomenon of short connection.

3, the memory is faulty

Memory of a chip or capacitance failure, sometimes will be able to power up after the host can be added, but there is no normal start "beep" sound, there is no memory alarm sound, long time can not start. Another situation is that if the CMOS settings when the frequency of memory or related parameters are set incorrectly, there will be power to add the host power, but is not to start and no alarm sound phenomenon.

Troubleshooting:

For such a failure we can first unplug the memory and then boot, if the host memory alarm, the CPU and host basic normal. Then try to clear the CMOS settings to see if the failure can be resolved, if the troubleshooting indicates that the cause of the fault is due to the memory parameter set in the CMOS error caused; if not, we need to use the replacement method, generally can be ruled out memory failure.

4. DMI data cannot be updated or ESCD data is not set to update automatically

The DMI (Desktop Management information) data is a collection of data stored in the BIOS chip to facilitate system calls and verifies that the DMI data is correct every time the system starts. I have not encountered a failure to boot the system because of DMI data errors.

ESCD (Extended System confirguation data) is stored in a CMOS chip to manage the collection of resource configuration data for a computer. With the rapid development of the computer and the application of Plug and Play technology, in order to avoid the conflict of resource occupancy, it is necessary to allocate limited system resources (such as address, IRQ,DMA, etc.) due to the rapid increase of computer peripheral resources, such as ACPI,APM,USB,MODEM,INC,VGA card, etc. Will cause the computer self-test time increases, causes the startup time to be too long.

In fact, most of the time, the computer board is not frequent, does not need to be a detailed self-test every time, so the computer designed ESCD data to simplify the start-up process of the computer, if the computer does not change the hardware, at the start of the computer directly call the ESCD data to allocate system resources to control the operation To save your computer's startup time.

However, when we change the hardware of the computer, such as changing the CPU type, replaced the memory, increased memory, acquired the optical drive, the video card, etc., if we do not force update ESCD data, then the computer will still be in the old configuration to allocate system hardware resources, At this point, there will be a failure to start properly or not recognize the newly acquired hardware. The solution we only need to enter the CMOS setup "Pnp/pci CONFIGURATION", the "reset ESCD" set to "Enabled" (after the computer is restarted, this option will automatically convert to disabled) but.

ESCD Data Update does not appear every time, only if you change the hardware hard, and in the CMOS settings will be updated, and the DMI data checksum will be on every boot.