Pentium 4 vs Pentium D
Although one might think that the last Pentium 4 processor and the Pentium D are worlds apart since it was basically a leap from the former to the latter, you would be surprised at hose similar these two are. You could say that they are almost identical. The major difference between these two is the number of cores inside. Pentium 4s are single core processors while Pentium Ds are dual cores. But their architectures are the same. The Pentium D basically had two Pentium 4 processors sitting side by side. They each had 2MB of L2 cache memory.
Since there are two of the same inside the Pentium D, it consumes much more power to have both cores running at peak. Motherboards that support the Pentium D had to cope with its higher power requirement. Another side-effect of the high power consumption is the much higher heat being generated by the processor. The two Pentium 4 cores, which are already very hot ones, running at full throttle translates to a TDP of anywhere between 90 to 135W. This is significantly higher compared to a Pentium 4 processor. It is often necessary for those who use Pentium Ds to install third party cooling solutions in order to maximize usage of the processor.
Since Pentium Ds had two Pentium 4 cores in them, you might be mistaken to thinking that it is able to perform tasks twice as fast as a Pentium 4. This is not actually true in practice as there are a lot of factors that affect performance. First, a lot of applications are not optimized to take advantage of two cores. Second, the design of the Pentium D meant that the two cores would be competing for the FSB bandwidth therefore degrading the performance even further. With that said, the Pentium Ds were still able to outshine the Pentium 4s in certain applications and even more so with multi-tasking.
It is already obvious but I would like to point out that the Pentium D is a more expensive processor than a Pentium 4. But despite the doubled number of cores, the price of the Pentium D is not really that far from the price of a Pentium 4.
Summary:
1. Pentium 4s are single core processor while Pentium Ds are dual cores
2. Pentium 4s run cooler compared to the Pentium Ds
3. Pentium 4s consume less power than Pentium Ds
4. Pentium Ds still perform better at multi-tasking than the Pentium 4s
5. Pentium 4s are cheaper compared to Pentium Ds