Benchmarks: Intel's 64-bit Pentium 4 660

AMD has led the 64-bit desktop processor field up to now with the Athlon 64 -- although there is, as yet, no shipping 64-bit Windows operating system, which is necessary to make the most of a 64-bit CPU. However, at the beginning of February Microsoft made Release Candidate 2 of Windows XP Professional x64 Edition available to testers, and the final version is due to ship at the beginning of April.

With its 6xx-series Pentium 4 processors, Intel has finally jumped on the desktop 64-bit bandwagon. Intel's EM64T architecture can implement Windows' x86-64 mode, and is also compatible with the AMD64 architecture. This means that you don't need different Windows operating systems to take advantage of 64-bit processing.

Intel's new processors offer some other innovations besides the 64-bit EM64T architecture. For example, all 6xx-series CPUs deliver 2MB of Level 2 cache -- double the amount on the 5xx-series chips. There's also improved power management in the shape of Enhanced Intel Speedstep Technology (EIST) and protection from malware infection via memory overflow thanks to the eXecute Disable (XD) bit.

The 6xx-series Pentium 4 chips have an 800MHz frontside bus (FSB) and are designed for use in standard desktop PCs. Intel is also offering a new Pentium 4 Extreme Edition clocked at 3.73GHz with a 1,066MHz FSB. This expensive ($999), high-end chip is only likely to appeal to a limited market -- mainly power users and gamers.

According to Intel, the 6xx-series Pentium 4s will replace the older line in the medium term. However, it may be some months before you can no longer buy 5xx-series chips.

Protection from worms and trojans

The new Intel chips include technology designed to prevent dangerous code -- contained in email attachments, for example -- being executed via buffer overflows. This is the eXecute Disable (XD) bit, which makes its first appearance on a mainstream Intel desktop CPU: until now, Intel has only implemented the XD bit in the server-class Itanium processor, and a limited number of Pentium 4 variants (those with the suffix 'J'). The Athlon 64, Athlon 64 FX and Opteron processors also offer this feature, which AMD calls No eXecute (NX).

Windows XP has supported the XD/NX feature since Service Pack 2 (Microsoft calls it 'Data Execution Prevention', or DEP). With DEP, the operating system provides a measure of inbuilt protection from worms and trojans, reducing the need to constantly install new security patches. Microsoft estimates that memory overflows lead to 50 per cent of all virus attacks; systems with XD or NX chips are therefore better protected against such attacks than those lacking this feature.

Improved power management

The new 6xx-series Pentium 4 processors benefit from improved power management in the shape of Enhanced Intel Speedstep Technology (EIST). The addition of this feature, along with improvements in the fabrication process, results in lower power consumption.

EIST provides similar functionality to AMD's Cool 'n Quiet technology in its Athlon 64 processors. If the system is in Idle mode, the voltage and clock frequency are reduced. As the CPU load increases, the voltage and clock frequency are gradually stepped up. The power consumption figures below demonstrate the effect of this technology. The Pentium 4 560 system without EIST (Intel D925XCV motherboard, 2 x 512MB Micron DDR2 RAM, MSI GeForce 6600GT, Maxtor Maxline III 250GB) uses 153 Watts in Idle mode, and this is reduced by 40 Watts when the EIST-equipped Pentium 4 660 is used instead. That's all the more impressive when you consider that Intel's new chip contains more transistors thanks to its 2MB of Level 2 cache. Compared to AMD's Athlon 64 4000+ (Asus A8N-SLI Deluxe), the Pentium 4 600 has closed the power consumption gap significantly, and is now only ten per cent behind.

* Maximum power consumption is measured using the CPU Stability Test 6.0 utility. If there is additional load on the graphics card, the system's maximum power consumption will be higher still. Note: the power consumption figures refer to complete systems with otherwise identical specifications.

Test setup

To evaluate the performance of Intel's top-end 6xx-series Pentium 4 (the 660 model running at 3.6GHz), we have compared it to AMD's Athlon 64 4000+. Both processors cost just over $600.

The Pentium 4 test system is built around Intel's 925XCV motherboard, which is equipped with 1GB of 533MHz DDR2 RAM. For the Athlon 64 system, we used the Asus A8N-SLI motherboard, again with 1GB of (DDR400) RAM. The other specifications are identical, comprising the MSI GeForce 6600GT graphics card and Maxtor's Maxline III 250GB SATA hard drive.

Benchmarking is based primarily around current programs that might be used in a typical digital home PC. Available 64-bit applications are also used to test performance. Some tests are run in parallel, in order to evaluate the processors' multitasking ability. Last year's top 3D games are also represented in the shape of Doom3, Far Cry and Half Life 2.

Most tests were carried out under Windows XP Professional x64 Edition RC2 (Build 1433). However, the production of an HTML picture gallery with Jalbum was done under 32-bit Windows: this application requires a Java Virtual Machine, which is not yet available for the 64-bit platform. We contacted numerous vendors about 64-bit Windows applications, with limited success. We do have some 64-bit applications in this performance test, but most are still beta versions.

Benchmarks: audio data, multitasking

Lossless compression of audio data is mainly of interest to hi-fi enthusiasts, who require the highest quality audio streams. This form of audio compression, which is becoming ever more popular in file sharing networks, can be handled by two programs: Monkey's Audio and FLAC.

Appropriate plug-ins are available for media players such as Winamp. APE files are provided with Monkey's Audio 3.99. FLAC files are compressed using the open source FLAC 1.1.1a utility. This program also has some optimisations for the Pentium 4 platform.

For the benchmark test, a compressed audio file (APE: Pink Floyd / Dark Side of the Moon, FLAC: J.S. Bach / Complete Cantatas) is first decompressed and then compressed again.

With Monkey's Audio 3.99, the Athlon 64 4000+ has the edge, and the picture looks similar with FLAC. However, the Pentium 4 profits from the optimised FLAC version 1.1.2, which is based on the Intel Math Library. This shortens the time for decompressing from 32.8 seconds to 23.2 seconds. When it comes to compression, however, the Athlon 64 takes 32 seconds less than the Pentium 4. In this mode, FLAC obviously has no Intel optimisation.

Multitasking test

When the two audio files are processed separately, the compression results favour the Athlon 64, which takes a total of 157.2 seconds (APE: 42.2s, FLAC: 115s) compared to the Pentium 4's 190.2 seconds (APE: 47.2s, FLAC: 143s). However, things look different if the compression takes place simultaneously. Then the Pentium 4 benefits from its HyperThreading (HT) functionality and overhauls the Athlon 64. Intel's chip takes 163 seconds with simultaneous processing compared to 190 seconds with separate processing. For the Athlon 64, the pattern is reversed: 157.2 seconds with separate processing extends to 170 seconds with simultaneous processing.

Benchmarks: video data

When it comes to video compression, the Pentium 4 660 is ahead of its AMD rival. Most applications in this area offer HT support, so the advantage of using the Intel architecture is hardly surprising.

TMPEG Enc Xpress 3.0 supports the Pentium 4's SSE3 instructions, which have yet to be incorporated into the Athlon 64 (this is slated for the next revision). Compression of the SVCD-format video file is therefore faster with the Pentium 4.

With Nero Recode you can copy a non-copy-protected 8.7GB DVD onto standard 4.7GB DVD-R media. To do this, the DVD data is compressed, a process that takes the Pentium 4 660 15:05 minutes in high-quality mode. The Athlon 64 4000+ takes over 20 minutes to complete the task.

Benchmarks: games