Computer won't start!!

[Yodle137]

I finally finished building my computer. i turn it on, and it turns on, however there is a very anoying sound, which i assumed was coming from my Zalman 9700. i turned it off, then took the cover off to see what was wrong. i turned it back on, and it sounded fine. so i turned it back of, put the cover back on, an tried to turn it on. it wont. i tried taking the cover back off, but that wont work. i have a Raidmax Sagita ATX case with an hec zephyr 650watt psu, intel q6700, saphire 3870 HD vidcard, and 4x1GB kingston Ram, Seagate Baricuda 250bg SATA HD, and two Liteon combo drives. help??

 

[Remeniz]

Make sure you mount the motherboard on these....

 

[Mr Spree]

if you did what Remeniz said, try taking the small round battery out of the motherboard, this will reset the board and leave it out for couple of minutes put it back in and try turning it on