The Bottom Line: The Pentium 4, Hyperthreading, 2.4Ghz Socket 478 processor has served me well for over four years and will give you solid browsing ability in Windows XP Professional.

Several years ago, I purchased two of these Pentium 4 2400 Mhz processors and some Intel D865GLC motherboards to completed a POV Ray animation. At the time, these processors were the fastest hyperthreading capable products on the market and were a big boost to the performance of my animation cluster.

A socket 478 motherboard can only get a maximum of 200Mhz actual front side bus speed so the goal of any processor upgrade is to either increase the clock speed or increase the on-chip cache size to reduce the number of memory calls during intense processing operations. Intel only released socket 478 processors with clock speeds up to 3.4Ghz. The higher frequency processors were also produced in limited amounts so competition on Ebay and Craigslist for these products is fierce. If you want to snag one of these computing gems, be prepared to bid high and watch out for sellers who have low reputation scores.

Performance Testing
Socket 478 processors presented computer enthusiasts with a unique set of limitations that were hard to remedy with by simply buying an expensive processor. The low on chip cache size results in increased memory calls that only evident when the processor is compared to the benchmark results of other Pentium 4 processors. To understand where the bottlenecks of this processor were, I used three different benchmarks: Super Pi, the BOINC Manager benchmark and MCS CPU Benchmark 2008. Each of these benchmarks stresses unique aspects of the processor and are heavily dependent on the supporting hardware around the processor like the memory, hard drive and motherboard chipset. In fact, the MCS Benchmark 2008 is only stable on the Windows XP Operating system.

The Pentium 4 2400 Mhz hyperthreading processor was installed in an Intel D865GLC motherboard with 1,024 Mbs of memory operating in dual channel mode. The motherboard chipset is very important because some chipsets in the Pentium 4 series support dual channel memory and can even pull fewer watts of power to increase the reliability of the system as a whole.

Super Pi V1.1 is an application that extrapolates the specified digits of PI into a text file. Since the task is both processor and file system intensive it can give you an idea of how fast your cpu is. Processors with large on-die cache sizes and high bus speeds tend to do better in this benchmark. The problem is the calculation is single threaded in this version so you only see the performance of one processor.

Here are the results of three runs at 1,000,000 digits of PI:
#1; 1 mins 11 seconds
#2; 1 mins 12 seconds
#3; 1 mins 11 seconds

The Boinc Manager benchmark is designed to stress every available thread on your computer to see how many computations per second it can perform. With the results, the Boinc Manager automatically assigns distributed computing projects to your processors. The benchmark has been improved by scholars at academic institutions over the period of several years and is now a very reliable metric of modern computing performance.

Here the results of three runs:
#1; 1122 floating point MIPS (Whetstone) per cpu, 2515 integer MIPS (Dhrystone) per cpu
#2; 1118 floating point MIPS (Whetstone) per cpu, 2491 integer MIPS (Dhrystone) per cpu
#3; 1124 floating point MIPS (Whetstone) per cpu, 2514 integer MIPS (Dhrystone) per cpu

The MCS CPU Benchmark 2008 will test the entire system to give you an overall score based on CPU and file system performance. The software suite is freeware which makes testing on a wide range of computer equipment possible.

Here are the results of three runs:
#1; 1684
#2; 1685
#3; 1684

The benchmark results are little humbling when compared to Socket 775 processors but you must remember this little processor is held back by its slow front side bus and relatively low cache size. Well, to be honest the processor just has to little cache! A Socket 478 Celeron 1.8Ghz processor can turn out a best of 2 minutes 20 seconds in SuperPi 1,000,000 and a rather dismal 943 Whetstone, 1252 Dhrystone on the BOINC manager benchmark.

I replaced this processor with a Pentium 4 3.2Ghz Socket 478 recently. I encourage you to examine the performance difference between these two processor by looking at the review published here: Pentium 4 3.2Ghz Processor Review

Two Core Steppings
The 2.4Ghz Northwood came in three core steppings: B0, C0 and D1. Usually, Intel releases another stepping of their processors to fix problems or to give an overall improvement to the performance of the processor. Intel normally does not release many details about why there are different microcode versions of their Pentium 4 processors so the IT community has few answers on this subject.

If you want to get a more efficient micro code on your Pentium 4 2400 processor, look for the SL6PM or the SL6QP which has the D1steppings. If you purchase the product on Ebay, your seller should disclose this information in this listing. Alternatively, I have in the past asked online retailers like Directron.com to verify a stepping by paying an extra $5 fee.

Specifications
Processor Core: Northwood
CPU Cores: 2 (includes hyperthreading core)
Die size: .13 micron
Hyperthreading: Yes
Frequency (Mhz): 2400
Bus Speed (Mhz): 800
Clock Multiplier (Mhz): 18
Dimensions: 1.38” x 1.38”
Socket 478 (mPGA478b)
Data width: 32 bit
Level 1 cache size: 12 k execution trace cache, 8 kb data cache
Level 2 cache size: 512 Kb on-die cache
Instruction sets: MMX, SSE, SSE2
You can find this processor under the following Intel part numbers: RK80532PC056512, QMT1, SL65R, SL66T, SL6GS, SL6PM, SL6S9, QUR8, QUS1, BX80532PC2400D

Summary
I have remained impressed with the performance of the Pentium 4 2.4Ghz 512Kb cache processor. The high speed, 800 mhz, front side bus kept my Intel 865GLC motherboard crunching Boinc workunits for several years. Now, in the year 2009, I have decided to upgrade the processor only because the 3.2Ghz Pentium 4 processor is so cheap on Ebay. If you need a solid performing, low thermal output, central processing unit for your Socket 478 motherboard, you just cannot go wrong with this processor.