Tried a different power supply had the video card checked put new motherboard and cpu in it, what's next the memory or the harddrives

The drives can simply be disconnected to check if they are the issue, however bad drives typically will not prevent a motherboard from POSTing. Bad memory will, although modern boards will usually complain about memory issues with beeps or led patterns.

Might also want to check the monitor cable.

Even if the video card has been checked, consider trying another one.

Also, does the monitor/cable work on another working computer?