This is my first build. Go easy on me. The components are:
Asus M5A78L-M LX Motherboard (onboard video)
Athalon II X2 270 CPU
Gskill Ram DDR3-1333
Rosewill 350w PSU
asus dvd-rom (pulled from working computer)
WD blue 150 GB hard drive (pulled from working computer)
The keyboard lights blink once when I turn it on but no video or it doesn't post, not sure. Have tried unplugging sata drives but no difference. tried swapping the ram around and using each one individually in slot A. I have rechecked if everything is plugged in correctly and it is. The internal (mobo) speaker is not plugged in since one wire fell off the speaker when I opened the package (rosewill). I also tried it with the front panel audio and USB unplugged.
Are the hard drives formatted? IF not do then do so. I suggest you unplug all the power cables and plug them back in again making sure they make proper connection and are snag tight. Then power up the PC. Don't plug the motherboard speaker if the wire is broken just leave it off.
Can you solder the wire back on? Or go to a local electronics shop and pick one up, they are pretty cheap. That way you may at least be able to tell if you are getting beep codes. It may narrow down what the problem might be.
If you dont have any luck identifying the problem through beep codes, my first suspect would be the PSU. It has no certification, only a 15A rail, actually rated for only 180w and made by an OEM i haven't heard of before.
Edit: Some quick calculations i'd say your PC draws about 160w, if the PSU is only good for 180w i'd say you're pushing it there, especially if it's come from an older PC, capacitor ageing will diminish its reliability and power output. Can you get hold of another (decent) PSU to try in the rig?