Northwood was the successor to the first Pentium 4 and Celeron core, Willamette. Since Willamette is distant history and you would be lucky to come across one, we will just start with Northwood.
Northwood doubled the cache of its predecessor, and comes with 512k of it if you have a Pentium 4 Northwood. If you buy a Celeron using this core it will only have 128k. They ran cooler, since they were based on a smaller process. While Willamette was manufactured using 0.18 micron technology, Northwood used 0.13 micron. This made it run cooler and required less voltage.
Another addition this processor bought to the Pentium 4 line was Hyperthreading. Hyperthreading is a technology developed by Intel; it works by duplicating certain parts of the processor, and allows better multitasking. It can also increase performance of Hyperthreading optimised programs. This technology wasn’t actually enabled until the 3.06GHz Pentium 4, and features in all 800MHz FSB Pentium 4′s. This technology was never enabled in Celeron.
Intel are now stopping production of their Northwood’s, so they can change over to the new core, Prescott.
Prescott is Intel’s newest core. Some people thought this would be the Pentium 5, but Intel stuck to the Pentium 4 name.
One version of Prescott comes with 1MB of cache, twice the amount the Northwood has. Although, if you buy a Celeron D, it will only have 256k of cache. Another version has 2MB of cache, but these are only used in Pentium 4′s and not Celerons. I will go into more detail later. Like the Northwood, this core has Hyperthreading, but again, only in Pentium 4′s. It does not feature in Celeron D’s. This core uses 90nm technology, even smaller than the 0.13 micron technology the Northwood uses. But unlike when Intel went to a smaller process and temperatures dropped, the heat actually went higher.
Prescott got the name “space heater” by many, and for good reason. Do a Google search for Prescott heat and you will see for yourself. This is a hot processor. In the Celeron D’s it isn’t as bad since there isn’t as much cache producing heat, but it’s a case of awful vs. bad. Intel aren’t the only ones to have problems with 90nm, nobody has had a easy time going to 90nm, its just Intel were struck worse because they ran their processors at such high clock speeds. This is the reason Intel have had to stop at 3.8GHz, Northwood can’t do it reliably, so Intel introduced Prescott to get to the higher speeds. But, because of the heat problem, 3.8GHz was the limit. Now Intel are having to find other solutions to increase performance. Of course, if you plan to run at stock speeds with no overclocking, this shouldn’t really affect you as long as you have a well ventilated case, but it is still far from ideal.
As I mentioned, this core is better suited to the Celeron D. Because of the cores improvements, the cache loss doesn’t affect performance as much as the Celeron with the Northwood core. The main reason is because of something called a branch predictor. I don’t really want to go into depth with the inner workings of the processor, since this is really just a quick technology guide. If you want to know about inner processor workings fully in detail, then you should check out Ars Technica.
As I said earlier, there are two versions of Prescott. One has 2MB of cache, one has 1MB. The 2MB version was the second version of Prescott, you can identify the processors that have 2MB of cache by their processor model number. If the number starts with 6, it has 2MB of cache. If it starts with a 5, it has 1MB of cache.
Not only do the 6XX processors have 2MB of cache, they also have 64 bit technology. If you really want 64 bit, then this is the processor for you. But, here is what I said about 64 bit in the AMD guide:
“But, you would be foolish to think you are completely futureproof. Lets say you buy a 64 bit processor today, and later on when 64 bit software phases out 32 bit software you buy 64 bit software to replace your 32 bit software. How old would your processor be then? Very old. Consider that nearly all Windows software is 32 bit apart from beta software, and you can see why it will take so long to change the world to 64 bit. This is why Intel are only just bringing their 64 bit processors to market, there is no rush for 64 bit processing.”
64 bit does bring higher performance, but there is no rush.
Celeron D doesn’t come with 64 bit technology yet, and only has the 256k of cache. All Celeron D’s at the moment start with the number 3.
Another thing to watch out for on both the Celeron D and Pentium 4′s is the J suffix. The J is Intel’s way of saying the processor features the XD bit, Intel’s version of AMD’s NX bit. This feature can stop some viruses, but don’t go disabling your antivirus program yet. You should have a read of this first. Bear in mind you need at least Windows XP SP2 to use this feature.
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