In this article, we look at the benefits or otherwise of 2, 4 and 8 core CPU’s. When does an 8 core really make a difference over a 4 or 2 core unit and is there any real benefit to the extra cost?

Background

All new desktops and workstations today have CPU’s with multiple processors or cores on them. This is a relatively new phenomenon which Intel introduced in the second quarter of 2005. Up to that time Intel’s CPU’s all had one processor and were based on an architecture called Netburst that had been around since the early ’90’s. Intel’s original intention was to take Netburst all the way up to 10GHz. By the time the company had reached 3.73GHz however, the amount of heat that the CPU was generating was so great that there was no adequate way of cooling a 4 GHz CPU that Intel was developing without resorting to radical methods like water cooling. The joke making the rounds at that time was Intel had diversified into making space heaters that occasionally doubled up as processors. Intel had dabbled with new computer case designs in an effort to aid cooling, but this effort was for the most part rejected by case manufacturers. They resented having to spend millions of dollars in retooling simply because Intel couldn’t get its heat issues under control. More pressing was arch rival AMD’s introduction to the market of CPU’s that were proving to be faster yet cooler than Intel’s offerings. This was a shock to Intel. The company had been dominant in the CPU market since the late ‘80’s yet its products were now being outperformed by a much smaller upstart with nowhere near the resources that Intel had.

Intel’s response was the Pentium D line of CPU’s. This was a crude product with basically two single core processors on a single piece of silicon. In truth, this was only a partial solution. The vast majority of applications at that time did not take advantage of multiple processors and since it was based on the same Netburst architecture, there was still the same heat issue to contend with.

Finally in the summer of 2006, Intel introduced the “Core” architecture, the company’s first new CPU architecture in over a decade. The Core architecture was 30-70% faster than previous generation CPU’s yet ran significantly cooler. The new architecture had been developed in Israel and was based on a design that was originally destined only for laptop CPU’s. This new design however was fast with such low energy requirements and heat output that it was modified for the desktop market. The resulting Core architecture was a resounding success, with CPU’s that were significantly faster than products from AMD. Intel quickly regained lost market share and since then, the company has never looked back. Intel has resorted to a two year development cycle for its CPU’s. Minor tweaks are made to the CPU architecture after the first year and a complete revision takes place after the second. In fact, the shock that Intel got from AMD in the first half of this decade has generated an atmosphere of real innovation within the company. They are now cranking out CPU’s, which are fast highly energy efficient processors. No other company in the world comes close either in terms of speed or efficiency.

In keeping with its two year timetable, Intel introduced a completely new architecture in November 2008 and named it Nehalem which again has made significant strides over the previous Core architecture.

The Contenders

In this review we examine how four different CPU’s fare when attempting to transcode “The Battle of Britain” from MPEG-2 to QuickTime. We use a highly popular application called handbrake to do this. We use handbrake because it uses all the physical cores available in a CPU. It is highly popular with users who want to watch their DVD’s on an iPod.

The four CPU’s we are testing are:

1. AMD Athlon64 X2 4800+. This CPU was introduced on May 31, 2005. This CPU was beloved by computer enthusiasts everywhere and was instrumental in destroying Intel market share and causing a real shake up at Intel. In benchmark after benchmark, AMD’s CPU’s wiped the floor with Intel’s offerings until Intel introduced a new architecture in mid 2006. At the time, it sold for around $700. We include it here to show just how far CPU’s have come in the last three or four years.
2. Intel Celeron E1500: Celeron is Intel’s brand name for its budget CPU’s. They are usually identical CPU’s to their mainstream brethren, except that some of the CPU memory or cache is disabled. The E1500 is a dual core CPU running at 2.2GHz and is based on the Core architecture.
3. Intel i7 920: This is a quad core CPU running at 2.66GHz with exactly the same architecture as the E5520 except that it can’t run in tandem with another CPU as the E5520 can.
4. 2 x Xeon E5520: The Xeon E5520 is a quad core 2.4GHz CPU based on the Nehalem architecture. We use two of them in an 8 core workstation.

Each CPU is tested with 4GB of RAM on Windows XP Pro.

The Results

Time taken for a CPU to transcode a 5.95GB MPEG-2 file to QuickTime in minutes (less is better)

The Conclusions

1. The most obvious conclusion here is that in video rendering and transcoding, more cores are better. CPU’s 3 & 4 are quad and 8 core machines respectively. CPU’s 1 & 2 are dual core. The quad and 8 core machines are four times faster at completing the same task.
2. CPU 1 has a frequency that is 10% slower than CPU 2, but since CPU 1 has 8 cores as opposed to the four of CPU 2, it is able to complete the same task 15% quicker. In other words when comparing CPU’s with the same architecture: More cores at a slower frequency are more efficient at transcoding than fewer cores at a higher frequency. This is one reason that I advise customers that plan to do a lot of video rendering and transcoding with their new workstation that it is better to choose a slower 8 core than a faster 4 core computer.
3. As stated above, CPU 2, the AMD processor that was beloved by gamers and multimedia power users and cost $700 in 2006 is barely faster than today’s Celerons which retail at less than $50. This is one indication of just how far processors have come in the last three years. If you are struggling to edit video or photographs with a computer that you bought before June 2006, you now know that all the marketing is not just hype! You do have an option.

Unfortunately, as implied above, not all applications make efficient use of all the cores in a CPU. Multiple CPU cores represent a significant paradigm shift in software programming because in order to make efficient use of all cores, the CPU has to be able to process instructions in parallel as opposed to sequentially as was the case with single core CPU’s. For example, games such as Crysis rarely make use of more than 2 cores. This is why companies that specialize in gaming computers don’t usually sell 8 core workstations – there is no performance gain so it is difficult to justify the extra cost.

As shown above however, photo and especially video editing take significant advantage of 4 and 8 core CPU’s. This is worth noting if you are a photographer or a videographer who has to work to deadlines – multiple core CPU’s will significantly improve your productivity. Finally, more cores mean better multi-tasking – the ability to run several programs simultaneously. This is especially true of the Windows 7 operating system which has been specifically developed to take advantage of CPU’s with multiple cores.