I have a p4 computer with u8668-d mother board.
There is no display,the key board lights are flashing together,and cpu fans are running,no light on power led.
How can I solve it? Is my mother board OK and the processor?

Any changes that either happened or that you perhaps made to your computer around the time that the problem started; particularly any Software or Hardware that you installed or setup.

Has the computer been moved?

Try unplugging all connections from computer and then reseat or put back all connections and try again

Also, try to unplug the computer while turned off and plug back in

I have tried unplugging all the cabels and re joining them,still the problem continues,

Do you have access to another monitor you can try and use on this? If so, connect another monitor just to see if the monitor is possible problem

Yes I have tried joining another moniter,but the problem still continues,my monitor works well with anpther cpu. Any other idea?
Please help me

Was the computer moved recently?

No it was not moved but I unplugged every thing and cleaned it with smooth brush,and plugged it again.it had a dislpay,I entered into BIOS and it hanged.so I pushed restart button,
And the display has gone.

Do you have a any disc that is bootable?

If you do, start the computer with the bootable disk to see if it will boot to the disk and not the operating system without issue.

Yes I have tried it,no result,as there is no display,but I can hear hard disk clinking with small sound,my cd drive,ram hard disk are working well.I have tested them in another computer

One of the last things to consider other than the system board itself would be your video card.

By chance, would you have access to another video card that you can swap out with the one you have in the computer now?

If so, changing the video card to a known working video card would narrow down to the video card itself or something with the system board.

But if everything seems to be working as you have mentioned but just no display and you have tested on another monitor and your monitor does work on another computer, this leaves the video card itself as the culprit

Nothing worked,thaks 4 all your help