No stand by power on my mother board and it won't start. is this my motherboard?

Well there are 5 components that could be the culprit.

1. The power receptacle- try plugging in something else into that outlet and seeing if it works.

2. The ECE (Power) cord. -Try switching out the cord and power up the computer.

3. The power supply- Try a different power supply with the MoBo, make sure they are the same form factor (ATX, AT, BTX)

4. The P1 connector, try switching the connector if possible (some PSUs don't let you, in which case switch the PSU all together)

5. The motherboard- Try the PSU with a different computer.

Also check all connections before you try troubleshooting, unsteated processor and RAM could also cause the computer to not start, check that all connections are secure and all cards are firmly in the socket.

I just went through that. The computer diagnostic schematic was...

1. take power strip, multi-plug out of the equation, plug directly into the wall

2. replace power button

3. replace PSU

4. replace motherboard

Number 2 and 3 fixed mine. But, I had a green LED onboard my mobo that lit up with PSU on. Computer would sometimes goto boot after warming up for 15 minutes with the PSU main power switch on, then it would start.

Adding a new PSU with more watts (used to be a 300, now a 500) does boot computer. It did improve sound volume a whole bunch.

Adam nailed it.

It sounds like the power supply to me, but without some diagnostics on your part there is no way to tell for sure.