I have a K7 M825G motherboard & a AMD 2300+ CPU & also a new case. I have put this together which makes my third pc I ever put together. Two are working fine , but this one I am having some problems with I hook the monitor to the pc and on the screen reads "video cable connected?" too which the monitor works just fine. The cooling fans & the CPU fan comes on but no beeps sonds like the hard drive & floppy don't even work.What could it be???