if that m2 was at 250mhz, that could have been either PR 333 or PR 366
Seriously, the PR ratings became ridiculous after about PR 266 (at which point, in integer tasks, they were actually realistic). The PR ratings are as follows:
PR133: 100/50, 110/55
PR150: 120/60, 125/50
PR166: 133/66, 137.5/55, 150/50, 150/60
PR200: 150/75, 165/55, 166/66, 180/60
PR233: 166/83, 187.5/75, 200/66
PR266: 207.5/83, 225/75 (6x86MX), 233/66 (6x86MX)
PR300: 225/75 (M-II), 233/66 (M-II)
PR333: 250/83
PR366: 250/100
PR400: 285/95
PR433: 300/100
(blatently ripped from
sandpile)