why wouldnt my memory work?

[NeptuneUK]

i got 2X1gb DDR2 modules and it er doesnt work... my mobo has two DDR and two DDR2 slots.. if i put either or both sticks in any DDR2 slot arrangement the PC beeps. my mobo says its supports DDR2 533 modules... which these are. they are crucial value.

 

[bellylard]

Have you updated to the most recent bios?

 

[NeptuneUK]

turns out that my overclocked CPU caused problems :S i put my old memory in and went to BIOS, the memory was set to "by SPD" and not overclocked... does this mean i cant overclock cpu much?