Thats queer, I've never heard of a GRND cable. What does it lead to, are you sure it isnt just the speaker cable?
Anyways try this
Is the 4(8?) pin cpu power connector plugged in?
Is the graphics card seated properly, is it plugged in to the PSU?
Is the ram seated properly, Try using only 1 stick.
Is the ram placed in the correct slots (Some i7 motherboards require ram to be installed in the slots starting with the one further away from the CPU) check the manual
Is the cpu fan plugged in?
Does the psu have a power sswitch, is it on?
I know these are simple, but you never know?
If your still having problems try building the thing outside of the case(some people call it "
breadboarding" idk why)
And finally, try just booting with only a cpu and heatsink and fan installed.
If you dont get any beeps from the bios speaker, then it is probably a bad psu, motherboard, or CPU