Enhanced Speedstep and Pentium 4

[Heini77]

I am about to buy a new PC and have to options for the CPU: Intel Pentium 4 521 or 630. The 630 is somewhat faster (which is not that important to me) and has Enhanced Speedstep, but is also more expensive (obviously). I will probably not need the extra power, but what I am interested in is whether the power saving will allow the PC to run cooler and thus more silent. Both CPU seem to have the same TDP, but Speedstep might make a difference.
Any experience with this?

[neb1211]

I don't have any experience with Speedstep but one of the benefits that Intel states is that the processor will run cooler.  I don't know how true that is but the main difference between the two processors you have listed is that the 521 only has 1mb of cache and the 630 has 2mb of cache.  That will probably give you more of a performance boost than the 200mhz increase in speed would.