Doesnt boot???????

Question

Have the above board and have tried 4400+ 2.3 ghz amd athlon x2 64 and the 5000 version. have changed all other components ie dvd drives memory etc. It refuses to boot up and give an initial boot screen display. have tried all conceivable things to get this too boot. It booted first time then would not boot again. have tried another board of same type and still the same problem. Can any body offer any ideas for this.