i have just bought a mother board it is a MSI K9MM-V - motherboard - micro ATX - Pro K8M800.
i removed my old motherboard and put this one in its place then i put a brand new AMD Athlon 64 x2 4200+ processor on it connected hard drive and dvd drive then placed graphics and sound card in connected all the power cables closed the case.
And when i try to switch it on i get nothing no power at all.

You can see the manual for the motherboard here
http://static.tigerdirect.com/pdf/MSI_K9MM-V_manual.pdf

I bought it from here
http://www.cclonline.com/product-inf...d=0&tid=k9mm-v

if anybody could give me a reason it not turn on i would be so grateful.

No power at all.

Nothing? No PSU LED? No PSU fan? Nothing?

If you are getting "something" verify that both the 24 pin main and the 4 pin ATX are connected.

Remove the Graphics card and Sound card. Both of these are on-board as well for testing.

No CPU fan?

If the Power Supply is not working then there is no need to look past that at the moment.

The first thing you need is a working PSU.

the psu is working i know this because i have tried it in another computer.
i am using a 20 pin and a 4 pin power supply as it says you can do this in the manual for the motherboard.
the only thing that gets power is the psu because the led on the back of it lights up.
i will try taking the video and sound card out and then i will get back to you but this will not be till tomorrow as i am going to get out of my tree tonight.
thanks for the help be back soon.

Try booting without any RAM installed.

Does it BEEP BEEP BEEP?

Sorry it took so long to get back to post but i have been busy as my son was born on Friday 16th so been very busy why i was at the hospital my dad found the problem though i was not using a power supply that was powerful enough.
so i used a better one i had and started straight away installed new os and and it is working just fine.
thanks for your help though.