While perusing one of my favorite [H]ardware sites, (Yes, that bracketed H is a clue to which site) I saw a review for a new Prescott-based Intel chip that had been released with little fanfare, the 2.4a, running at 2.4GHz with a 533MHz FSB. It came with the increased pipeline length and additional cache of the Big Brother Prescotts, yet it did not have Hyperthreading or the 800MHz FSB that they enjoyed. I read further that this puppy was going to be a great chip for enthusiasts, as the site’s reviewer had been able to achieve a 900MHz overclock with this chip on stock cooling and voltage settings. 900MHz, I thought? That is a 3.3GHz chip for the low, low price associated with a 2.4GHz processor! If this was true, I had to try one out…
Why did I buy this processor?
I admit, I was caught up in the hype. I wanted a processor to run 900MHz overclocked from its stock speed, and I could do that with the low, low price of $138. I bought some Corsair Value Select PC3200 RAM to go along with the processor and an MSI PT880 NEO-LSR motherboard that is very low dollar and Prescott ready. My other motherboard, the ABIT IS7-E, did not handle the heat of the Prescott 2.8e I had earlier, so I thought it better to try another board. Also, I was going to keep either the 2.4a or the 2.6c I already owned, so may as well buy a start on the complete system that would be for sale!
Specifications:
NOTE: This is the meat and potatoes section for the enthusiast in some of us. This will explain what differentiates this chip from all the rest, and may not be completely interesting to all readers. For those of you who have read my 2.8e Prescott review, some of this will be very similar, but it is worth restating. Some of this is very different, as this is not the typical Prescott, either! If you just want to see how the chip performed, skip down to the Performance section below
Prescott in general
This processor is part of the Prescott family of chips based on the new 90 nm process. Running this small of a process allows for more and more transistors on a smaller or same size die, which allows for more calculations and thus higher performance, in general.
For the Prescott family of chips, Intel increased the integer pipeline from 20 to 31 slots, which in essence slows the processor down. By simply increasing the pipeline length, the processor speed should actually be slower. This is due to the fact that all of these slots are not filled instantaneously with data(latency). If they were, this would actually speed the processor up, as you can now have multiple data threads waiting for further crunching. Not good if they are not filled, but this does allow for higher GHz as well. The estimation is that the Prescott family of chips will be able to top out around 4-5GHz when it is all said and done!
The 90 nm process allows for more cache to be crunched into the smaller die, and thus faster access to frequently used data for the processor to crunch. On-die memory, or cache, is accessed at the speed of the processor’s rating, in this case 2.4GHz. Compare that to the 533MHz of the FSB, and you can see why more on-die cache is so good! This is also what delineates the Extreme Edition chips from one another; they have a whopping 3MB of L3 cache! It does come at a price, though, as those chips are upwards of $800/each. The end result of this is that since the Prescott holds 1024Kb of L2 cache(twice as much as the previous Northwood cores at 512kb), this processor should be faster than the previous core.
The smaller process, while decreasing costs, also added additional transistors on the chip, as mentioned above. This allows for faster speeds, but also generates heat. The heat generated has to be moved away by an active heat sink and fan or else the processor will fry! In the olden days (not actually too long ago) a simple heat sink would suffice. Soon we will need a watercooling unit or refrigeration unit for every home computer, and that is just for the processor! It may be a while before that statement is a reality, but you certainly don’t want to lock your computer in a small, low airflow cabinet anymore!
The Prescott family of processors introduce two other items, a new branch predictor (which is supposedly better) and SSE3, 13 new built in directions that the programmers can use to speed up their systems in the future. The branch predictor was actually needed to help make the increased integer pipeline run faster, as without this and the increased L2 cache these processors would have been abysmally slow. The SSE3 instructions may help out in the future, but for now they are not used very much.
What about the 2.4a in particular?
As I said above, this chip is not your everyday Prescott. The differences noticed are in Front Side Bus (FSB) and HyperThreading (HT).
FSB
Front side bus is the speed at which your processor talks to your RAM, and the higher it is the faster your bandwidth. The faster your bandwidth, the faster your computer performs. RAM is the Random Access Memory sticks that you have in your system, and they are essential to run any system. Remember the L2 cache? There is only 1MB there, and the processor runs so many calculations that it needs a secondary storage facility for data. RAM is that storage facility. The processor sends intermediate data to the RAM and calls for it when needed. Both sides of this transaction take place across the FSB, so the faster, the better.
The Big Brother Prescott’s, of which I have owned the 2.8e, use a FSB of 800MHz. The newer Northwood cores, of which I currently own the 2.6c, also run at this 800MHz FSB. If you overclock one of these processors to 250MHz system clock(which I have done with both of these processors), this gives you an effective FSB of 1000MHz, or 1GHz. This is because the FSB of an Intel P4 is quad pumped. (250*4 = 1000, see?) This works out to amazing bandwidth/performance, as with Dual Channel PC4000 RAM I have seen up to 5900MB/s of data transferred across the FSB.
In the case of this little brother, they rated the FSB at 533MHz, which means the system clock is only starting out at 133MHz(133*4=533). This means that your bandwidth will never be as high as the Big Brother Prescotts or Northwoods with 200MHz system clock, or 800MHz FSB. However, this chip also costs less, and you can pair it up with some nice PC2700 or PC3200 at overclocking speeds, either of which is much cheaper than the PC4000 for the higher speed chips. This means that you can get great performance for less money…
HyperThreading
Hyperthreading technology allows the OS to simulate two processors, and thus have multiple task threads working at one time. The intel website can explain it much better than I:
My experience with the Hyperthreading so far is neither positive nor negative. I have noticed no difference in my usage with or without the Hyperthreading enabled with my 2.6c or 2.8e. The fact that this processor does not have it does not bother me in the slightest, but if you are building a computer to last you the long haul, this may be a deal breaker for you.
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