I've made sure that the HDD was plugged into the correct SATA connector, used the sata cable that is connected to the DVD drive (and he is found by the mobo) and the HDD still is not detected when the DVD drive is still detected with another cable.
I've resetted CMOS and all. I can hear the disk spinning, seems like it starts to spin, clicks, then re-starts spinning a couple times then it all stops and I got the Hard Disk Error message saying that no Hard disk was detected. The more and more I think it's a HDD problem.
The shitty part is we have no desktops at home, I'm using a MacBook right now, so I have no way right now to plug in my HDD somewhere else to see if it works on another computer.