That's a classic question...

Maybe the newer core has more headroom for O/C...also depends heavily on board and ram as you have to go over 133 FSB. There are a lot of version...what socket is it?
SL44J 933.00 MHz 133 MHz 0.18 micron cB0 256 KB 370 pin PPGA
SL52Q 933.00 MHz 133 MHz 0.18 micron cD0 256 KB 370 pin PPGA
SL47Q 933.00 MHz 133 MHz 0.18 micron cB0 256 KB pin SECC2
SL4BT 933.00 MHz 133 MHz 0.18 micron cC0 256 KB 495 pin SECC2
SL5DW 933.00 MHz 133 MHz 0.18 micron cC0 256 KB 370 pin PPGA
SL4C9 933.00 MHz 133 MHz 0.18 micron cC0 256 KB 370 pin PPGA
SL5U3 933.00 MHz 133 MHz 0.18 micron cD0 256 KB FC-PGA2
SL69K 933.00 MHz 133 MHz 0.13 micron tB1 512 KB 479 pin H-PBGA
SL4ME 933.00 MHz 133 MHz 0.18 micron cC0 256 KB FC-PGA
SL448 933.00 MHz 133 MHz 0.18 micron cB0 256 KB S.E.C.C.2
SL49J 933.00 MHz 133 MHz 0.18 micron cB0 256 KB FC-PGA
SL4KK 933.00 MHz 133 MHz 0.18 micron cC0 256 KB pin SECC2
I think the cD0 revision was a decent overclocker...this was the only 0.18u core capable of 1.13GHz...