i6000D 3Dmark03 scores

Can anyone tell me how when i oc my x300 128mb card with centrino hardware control to 400mhz on the core and 216mhz on the memory that i score 3106....and when i oc it with ati tray tools to 400mhz on the core and 300mhz on the memory that i score 3026....how is that i score 100 points less?

thanks

it probably means the OC is not stable..or maybe the card is overheating and its throttling