Intel Core Duo for Desktops

Intel Core Duo for Desktops
(Meet the Viiv Platform)

It’s not a new idea to use a mobile processor in a desktop PC. PC enthusiasts were casting interested looks at mobile processors from the Pentium M series ever since Intel had transferred its desktop CPU series to the NetBurst architecture. As opposed to it, the Pentium M was based on the P6 architecture that had been employed in the highly successful Pentium III CPU series. First experiments of installing the Pentium M on desktop mainboards (made possible by ASUS who introduced a special adapter; read more in our article called Intel Pentium M 780 as Heart of Your Desktop PC, with ASUS CT-479 Adapter) showed that this idea did make sense. Senior Pentium M models had a normal performance even by the standards of desktop computers and were even better than CPUs with the NetBurst architecture in other characteristics, e.g. in heat dissipation. Unfortunately, such systems never achieved the status of a mass-user solution, mostly due to opposition on the Intel side. The company didn’t look favorably at experiments of that kind and made steps so that the adapters and mobile processors were not widely available. Moreover, processor architectures began to progress towards dual-core designs, so the efficiency of using mobile CPUs in desktop computers was put in doubt.
The situation changed this spring when dual-core CPUs conquered the mobile market after their release at the beginning of this year. As a result, Intel produced a new generation of processors for notebooks which met today’s requirements but were still based on the efficient P6 architecture. Another fact confirming the efficiency of this architecture is that Intel’s upcoming processors for all the market segments (Conroe, Merom and Woodcrest) are going to have a core micro-architecture similar to the one the Core Duo and Pentium M have. But until the Conroe is released, the mobile Core Duo may prove to be a lucky choice for a desktop computer.
Some mainboard manufacturers caught at the opportunity and began developing Socket 479 products compatible with the Core Duo. AOpen was the first of them, announcing its Socket 479 i975Xa-YDG mainboard on Intel’s top-end i975X chipset. Unfortunately, they only made an official announcement and issued a few samples. The i975Xa-YDG remained on paper ever after. Yet the Core Duo eventually found its way to desktop computers and it was Intel itself who helped it with its Viiv platform!
The Viiv platform is intended by its developer for use in home multimedia centers, in computers that are to be the entertainment center in the Digital Home. Besides providing opportunities to watch movies and TV, listen to music, work with digital images and play games (arcades, mostly), computers built according to the Viiv concept must have a home-oriented exterior design and provide enough performance, but must not produce much noise. And for these purposes there is nothing better than Intel’s mobile processors! Of course, Viiv computers can also use CPUs of the Pentium D family with the NetBurst architecture, but it is more reasonable and logical, considering the intended applications of the Viiv platform, to use modern dual-core processors of the Core Duo series that have been so successful in notebooks as part of the Centrino Duo platform (read more in our article called Centrino Duo Mobile Platform Review).
Realizing this fact, Intel gave the green light to mainboard manufacturers who were willing to produce Viiv-compatible Socket 479 products. And the result is that there should soon appear desktop mainboards with support for Core Duo processors, and this is not the single thing they will have in common. They are all going to be designed in Micro form-factors and to have an integrated graphics core and enhanced opportunities to connect to external peripheral devices. Although neither of these traits is indeed required from a Viiv-compatible mainboard, yet most manufacturers view the new multimedia platform in exactly this light.
Today you are going to see one a Viiv-ready mainboard ASUS offered for us to test. The N4L-VM DH looks much alike to the typical portrait we’ve drawn in the previous paragraph because it is based on the integrated i945GM chipset. However, we are not as much interested in the Viiv platform as we are in ordinary desktop systems where this mainboard can also be used. So, this review is about how useful the mobile processor Core Duo can be in a normal desktop computer. You’ll see how it copes with typical desktop applications and learn if the Viiv platform deserves any interest from PC enthusiasts.

PCB Design:

So, the ASUS N4L-VM DH mainboard combines rather rich functionality with the Micro-ATX form-factor. Of course, the developer had to solve a difficult problem of placing all the necessary chips and connectors in the limited area, so we can hardly expect that all the components are placed on the PCB in a manner convenient for the user.
And still, there are very few things about the PCB design of the ASUS N4L-VM DH we can complain about. The main components are all properly located. It is also good that almost all the connectors, including both the power connectors, are placed at the front and left sides of the PCB.

What we don’t like is how the additional Serial ATA controller from JMicron and its ports are placed. One of the controller’s Serial ATA ports is located at the mainboard’s back panel and the other one is near it. As a result, you may find it difficult to use these ports: you need a power source for the external hard drive to use the former and you just don’t have free access to the second port to use it.
The memory slots are located in a somewhat odd way, in between the CPU socket and the mainboard’s back panel. This placement isn’t likely to cause any problems, though.
The CPU socket, memory slots and chipset’s North Bridge are all densely packed in one area of the PCB and so most of the heat generated by the platform (if you use the integrated graphics core) will be accumulated in this area. Since the ASUS N4L-VM DH is meant for use in Viiv systems that are to be small, this looks reasonable. It’s not very difficult to provide for efficient cooling here.
The chipset’s North Bridge is equipped with a massive aluminum heatsink without a fan. The CPU fan included with the mainboard is made of aluminum, too. Considering the low heat dissipation of Core Duo and Core Solo processors (especially in comparison with that of the Pentium D family), it would be unreasonable to use advanced cooling solutions here.

The heatsink of the CPU cooler has a 60x60mm base and 21 ribs, 22 millimeters in height. A 60mm medium-speed fan is installed on top; its maximum speed is 3500rpm. The heatsink’s base is equipped with a frame to protect the die from chipping (the die of modern processors of Core Duo and Core Solo series is not covered by a heat-spreader).

BIOS and Overclocking:

The ASUS N4L-VM DH was tested with the latest version BIOS as of the time of my writing this review (version 303 dated April 25, 2005),
The BIOS of the ASUS N4L-VM DH mainboard is based on AMI’s microcode and has the same setup interface as other AMI-based BIOS Setups. You can configure the system’s main units here, but that’s not very interesting.
We were more curious about the overclocking options provided by the mainboard, but were somewhat disappointed on that point. Positioned by its manufacturer as a multimedia entertainment center, the mainboard lacks a bulk of overclocking-related options in its current BIOS versions.

In fact, the BIOS Setup only allows changing the FSB frequency, but you have no control over the voltage and frequency multiplier of the CPU. And even this adjustment of the FSB frequency doesn’t work too well. The default FSB frequency of Socket 479 Core Duo and Core Solo processors is 166MHz, but the maximum FSB frequency the ASUS N4L-VM DH remains stable at is only 182MHz. The mainboard just refuses to start up at a higher FSB clock rate.
Besides the option of adjusting the FSB frequency, even though in a very limited range, the mainboard allows changing the voltage of the memory modules. Not quite clearly what for, the BIOS Setup can increase this voltage from the default 1.8V to 2.1V. Besides that, you can manually set up the memory timings here. The memory frequency, however, cannot be changed. It is always set up automatically depending on the SPD information written in the installed DDR SDRAM modules.
All of this means that the ASUS N4L-VM DH mainboard isn’t a playground for overclockers. For example, we could only manage to speed up our Core Duo T2600 from its default 2.16GHz to 2.37GHz by increasing the FSB frequency to the maximum of 182MHz.
So, the maximum frequency growth you can achieve on this mainboard is 10% only – not quite what an overclocker would be satisfied with.
Regrettably, Intel’s Viiv platform is not meant for overclocking at all while the manufacturers of mainboards for multimedia computers do not expect such products can attract PC enthusiasts.

Software:

ASUS’s mainboard always come with a big software pack, and the ASUS N4L-VM DH is not an exception. There are at least two interesting utilities on the CD you receive with this mainboard.

PC Probe:

This is a Windows-based hardware monitoring utility:

ASUS Update:

This Windows-based program can automatically update the mainboard’s BIOS. The version of the utility you receive with the ASUS N4L-VM DH cannot update the BIOS directly from the Internet – only from a file on your hard drive.

ASUS doesn’t offer any programs to control the FSB frequency from Windows, i.e. for overclocking. Instead, the software CD included with the N4L-VM DH contains a utility to change the image shown during the POST procedure and an exclusive ASUS screensaver.

Closer Look at Core Duo T2600:

In this article we are going to compare dual-core processors with different architectures: Athlon 64 X2, Core Duo and Pentium D. Therefore we decided to take the top models from all three processor families for our test session. The fastest CPU in the Intel Core Duo family at the time of testing was Core Duo T2600 with the nominal clock speed of 2.16GHz. It will be our today’s second main character after ASUS N4L-VM DH in our today’s review.

Core Duo T2600 processor is based on Yonah core, features 2MB L2 cache shared between the two cores and was manufactured with 65nm process. The CPU works with 667MHz bus and its nominal core voltage lies between 1.25V and 1.4V when it runs at nominal frequency. The maximum typical heat dissipation of the Core Duo T2600 processor is 31W, just like any other CPUs from the same family. You can read more about the architectural peculiarities of the Core Duo processor in our article called Centrino Duo Mobile Platform Review. Today we will just give you a brief list of its major characteristics:

Core Duo T2600
Frequency
2.16GHz
Packaging
478 pin PPGA
Vcore
1.25V - 1.4V
Bus frequency
667MHz
Typical heat dissipation
31W
Core stepping
C0
Maximum case temperature
100o C
L2 cache size
2MB
Production process
65nm
Hyper- Threading ( HT)
No
Intel Enhanced Memory 64 Technology (EM64T)
No
Enhanced Intel SpeedStep (EIST)
Yes
Intel Virtualization Technology (VT)
Yes

The Centrino Duo processor looks somewhat unusual. The thing is that mobile processors come without the top heat-spreader lid protecting the die against mechanical damage. However, end users do not usually deal with the installation of mobile CPUs, so they do not really need the protective heat-spreader.
The diagnostic CPU-Z utility reports the following info about the Core Duo T2600 processor:

Here I would only like to add that in power saving mode the clock speed of the Intel Core Duo T2600 processor drops down to 1GHz and the Vcore – down to 0.95V.

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