computer startup problem

You say the PC is running normally? The POST is cycling through the drive sequence, correct? It would help if we knew a bit more about the rig you built...components and such. Things to try;

1. The monitor is securely plugged into the video card, with no bent pins.

2. The video card is seated properly in it's slot and has the required (if applicable) power connectors attached firmly. Note, if the card requires multiple power connectors, make sure you use two different plugs and not splitting one Molex connector with an adaptor cable.

3. Make sure all the required power plugs to the mother board are attached.

4. If the board has on board video and you're using an PCI-X card, try plugging the monitor into the on board connector. If it's working, enter the BIOS and disable the on board video (exit and save). Then power down and plug the monitor into the PCI-X card.

5. If everything checks out and there's still no image on the screen, try a different video card to make sure the first one isn't dead

6. If there's no image with the second video card, swap the monitor...'cause things can work one minute and die the next.

7. Worse case scenario...the PCI-X slot is screwed up. BTW, you did use the stand offs, when you installed the mother board, right???

You could try a re-seat ram + clear cmos,

My personal Fave.

I tried all of that and yes i used the stand offs.mejia13fernando

Well, if ya tried all of the above, try swapping the PSU...and while you're at it, disconnect the optical drive(s), booting only with the primary hard drive. I remember someone telling me a bad optical drive once prevented his system from booting. It's not quite the same problem you're having, but it can't hurt to rule it out. After that, I'd try a different hard drive, because there have been chipset/hard drive conflicts in the past. It's not unheard of for a person to get a bad MOBO right out of the box, but it's fairly rare. If you have a secondary system handy and the time, test all the system peripherals (HDD, optical drives, etc...). If everything else is working, you may have a bad MOBO.