Always restart when boot

[naruponk]

Hi,

My pc is

E2160
P5LD2-X/1333
Seagate 40GB
Kingston 667 1GB
GF7200

I have installed Mac OS X 10.5.6, the installation is going fine and completed successfully
when I restart machine, It does going to booting but my PC restart again
Then I try to use -x -v and -v to see what happen,
I can't see anything because it restart before I can read last line

Any suggestion ?