we really do need more information to help you.
- Did you install an OS yet?
- If yes, did you install the chipset drivers for your motherboard yet?
- Have you ever successfully booted into the OS if you DID install one already?
- If yes, boot into safe mode by tapping F8 as the computer boots up.
- Tell us exactly what the screen says as you go through. "ATI" could be a video card issue, could be an ONBOARD video issue, or it could simply be a hardware problem.
Your system should also have an onboard speaker of some kind. During boot-up, the computer goes through the POST process and will beep out error codes if there are any. Listen for beeping and note the types of beeps (2 short, 1 long, etc etc). Check your motherboard manual to see what the error code means. Usually a single beep means it POST'd fine.
Also, you could just clear your CMOS. You may have screwed with something in the BIOS inadvertently (sp?) There is probably a CMOS jumper on your mobo that you must toggle... then pop the battery out of the board for a few mins. Replace battery, switch back jumper... boot back up.