My one year-old Thinkpad A31 has a Pentium 4-M, 1.6GHZ processor which is a Northwood mPGA-478B pin, family F,model 2, core stepping C1 (dont know the sSpec #). I want to upgrade this processor by using a Pentium 4-M, SL6CJ processor. This looks identical to the original one except it is a 1.8GHZ and has core stepping B0, which I believe is an earlier core stepping version. -Does anyone know if this substitution is recommended? -How bad are the properties of the B0 stepping compared to the C1 ? -Is it worth going ahead with this upgrade? In other words, is the gain in speed worth the handicaps of the earlier core stepping version of the processor? Would appreciate any help you can give.

Hardly any gain by making the so call "upgrade" for 200mhz. The C1 is newer stepping than BO, the video codecs are different in between the two, i.e. whatever DVD, MPEG program you are doing. Anytime you want to "upgrade" try using the 50% speed improvement rule. Otherwise, you would be disappointed.

Thanks, real_cool. I guess you are right...that's the reason I am cautious. In fact, I found a 2.0 and a 2.2GHZ processor with the newer stepping (C1), but their thermal power is 32W and 35W respectively, compared to the max 30W of either the 1.6GHZ or the 1.8GHZ. Which raises the question : will the existing cooling fan be capable to do its job? Attempting to change the fan,I think, will complicate things, this being an IBM laptop, etc... What do you think ? Thanks, anyway