Mac Pro mid 2010 no boot no chime no keyboard light power issue

hi

my Mac Pro mid 2010 does not Boot

it has no chime, no power to turn in the led caps lock light on the keyboard but the mouse led turns On and when I plug in my external hard drive the led lights on the hard drive come On. The white led light next to the power button on the Mac is always solid white when on (Even if I take out any parts of the Mac eg ram, hard drive, graphics card).

i have checked the graphics card on my pc and it works perfectly, the ram i has swapped with my pcs ram ddr3 which I know works. The hard drives have OS X leopard from Installed My power Mac g5 and so it works. I changed the battery but nothing helped. i have done smc and pram resets. But no display is occurring, I know the display works, I used dvi , mini display port, vga i also plugged in a graphics card from my pc to The Mac but did not help (I don’t know if they are supposed to be compatible or if any old graphics card works in the mac). I have tried several hard drives. Also when I boot with no ram the led diagnotic lights don’t come up next to the ram slots. Only when I turn on the computer does a red light flash on the processor board And 2 lights on the backpane board. Fans run and the optical dvd drive makes sound but cannot be controlled via keyboard. I know the keyboard, mouse works.

What should I do next?