HWsupport.com have found a great Intel Pentium 4 steppings guide. BUILDING A PC that uses a Pentium 4? System integrators will be pleased to hear that Intel has now produced a handy little table that will let you find out straight away which processors are of the C1 stepping variety.

You will recall that Pentium 4s using the B stepping suffered from the prefetch bug that slowed them down a wee bit. Make sure you buy a C1 chip if you're going for a new one. Intel Pentium 4 Steppings Guide