ASUS P5QL Pro doesn't detect SATA HDD

i just typed up a whole entire body for this thread and i accidentally closed the IE window. So i'm gonna make this as quick, but thorough as i can. also, this is my first MajorGeek thread. so show some new-member love

Me and a buddy finished assembling a computer a few days ago (specs below). We put everything together and turned it on. It booted up BIOS, but didn't detect any SATA or IDE hard drives that I connected. The only thing it would detect was an IDE DVD drive that i hooked up. (i know the hard drives are fine because they work properly in other computers.)
after an entire weekend of fiddling with BIOS settings, and testing various hard drives, we dropped off the PC to our local repair shop. after a day of testing, the repairman called me up and said he narrowed the issue down to a faulty motherboard. the model of this faulty motherboard was an ASUS P5KPL-CM.

after i got the news, i went out and bought myself a brand new ASUS P5QL Pro. we got home, swapped the boards, hooked everything up, then booted up the computer. BAM. Same exact issue. didn't detect any hard drives that I connected. I continued playing with BIOS for a few hours but still couldn't get anything.
i still haven't gotten my board to detect any hard drives! I'm dying to get Windows installed and have my PC up and running.
please help me.
here are my specs


ASUS P5QL Pro
Intel Q6600 2.4GHz Quad Core
Kingston HyperX 4GB 2x2GB PC28500 DDR2
ATI Radeon HD3650
160GB SATA HDD
40GB IDE HDD
IDE DVDROM Drive

any other information is available upon request