Build a Compact Pentium M PC

By Loyd Case  |  Posted 2005-07-12 Email Print this article Print
 
 
 
 
 
 
 

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Build It: Take a mobile Pentium M processor, mix in a micro-ATX case, add a socket 479 adapter card and your favorite PC peripherals, and stir. The result: A cool running, relatively quiet compact PC that actually kicks butt in PC games.

Something Old, Something New
Last year, Dave Salvator took a look at the inner workings of the latest Intel mobile processor, code-named Dothan. Dothan is the second-generation Pentium M processor, built on Intel's 90nm manufacturing process and sporting 2MB of L2 cache. Later, Jason Cross investigated Dothan's performance in his review of the Pentium M and Aopen's 855GME motherboard, which used Intel's earlier 855 mobile chipset. Since then, Dothan has undergone a front-side bus (FSB) speed boost to 533MHz effective (133MHz actual clock), and Intel has also introduced the mobile 915M chipset as a part of the company's Sonoma mobile computing platform.

As Jason discovered, the Pentium M processor makes for a surprisingly good desktop platform. Although some 915M desktop motherboards were announced at Computex recently, they've been slow in trickling out to the market, probably because of the hot demand for 915M based laptop PCs. ASUS has stepped up to the plate, with its CT-479 adapter card, which allows you to plug a Pentium M processor into a socket 478 motherboard.

Currently, the CT-479 is certified only on two ASUS motherboards, the P4P800 and P4P800-VM. We thought the P4P800-VM plus Pentium M combo would make for the core of a spiffy small-form-factor PC, so we built one, and we're here to share our experience with you. We built the system with an eye towards benchmarking the system in a comparable way with past processor platforms we tested. We won't go into a big song and dance about how we chose most of the components. But let's take a look at the key components we used and how we built the system. Continued...

We begin with the Pentium M model 770. This is Intel's top-of-the-line mobile processor today, and it clocks in at 2.13GHz, and sports a 533MHz front side bus. Like the original 400MHz FSB Dothan, it's built on a 90nm manufacturing process and integrates 64KB of L1 cache and 2MB of L2 cache. Like all Pentium M processors, the 770 also integrates a sophisticated pre-fetch unit, SSE2 instruction set, hardware Execute Disable Bit support and Intel's Enhanced SpeedStep power management technology. The Pentium M currently costs around $700—quantity 1.

Here is a rundown on the list of components for our systems:

Intel Processor Systems Athlon 64 Systems
Processor: Pentium Extreme Edition 840; Pentium 4 Extreme Edition at 3.73GHz; Pentium 4 670 at 3.80Ghz Athlon 64 FX-57 at 2.8GHz; Athlon 64 FX-55 at 2.6GHz; Athlon 64 X2 4800+ at 2.4GHz
Case and power supply: Aspire X-QPack Aspire X-QPack
CPU cooler: Standard Intel Thermalright XP90, Vantec Stealth 92mm fan.
Motherboard and chipset: Intel D955XBK, Intel 955X chipset ASUS A8N SLI (nForce 4 Ultra SLI chipset)
Memory: 2 x 512MB Corsair DDR2/667 at CAS 4-4-4-12 2 x 512MB Corsair XMS Pro Series DDR400 (CAS 2-3-2-6)
Graphics: Nvidia GeForce 6800GT PCI Express Nvidia GeForce 6800GT PCI Express
Hard drive: Seagate 7200.7 160GB SATA Drive Seagate 7200.7 160GB SATA Drive
Optical drive: ATAPI DVD-ROM Drive ATAPI DVD-ROM Drive
Audio: Sound Blaster Audigy 2 Sound Blaster Audigy 2
Operating system: Windows XP Professional with SP2 Windows XP Professional with SP2

To enable the 770 to work in a socket 478 motherboard, ASUS supplied us with a CT-479 socket adapter board. The CT-479 can be found for around $50, and supports both 400MHz- and 533MHz-FSB processors. The CT-479 may work with a variety of socket-478 motherboards, but is currently only certified with the P4P800 and P4P800-VM, both socket-478 boards based on Intel's older 865G chipset. The CT-479 also requires that its own 4-pin molex power connector be attached to system power.

The CT-479 ships with a processor cooler that uses a low-noise fan and is specifically designed to work in a socket 478 HSF bracket with the CT-479 installed.

We used the Micro ATX P4P800-VM motherboard. This is a pretty basic 865G board, with somewhat limited I/O—it lacks FireWire and Gigabit Ethernet. But it does have four rear-panel USB 2.0 connectors, dual-channel DDR400 support and a pair of Serial ATA 150 connectors. Continued...

Building a system requires a case and power supply. We didn't really want to spend an arm and a leg for a case and power supply. In our search, we stumbled across the Aspire X-QPack, a spiffy-looking compact cube-style case with a built-in 420W power supply. The Aspire case even comes with a foldaway handle—just the thing for transporting the system to LAN parties.

The case also ships with transparent side panels. While ours arrived in a silver-and-black motif, it is also available in a variety of colors.

The 420W power supply is unusually compact and light—probably not suitable for very high-current demands, but we're not running an SLI system here. The 12cm rear fan sports blue LED lighting.

The case is constructed from lightweight aluminum and acrylic, and is very light at less than nine pounds, including the power supply. Note that the power supply is the older, 20-pin ATX 2.0 variety, which lacks dual 12V rails. That's fine for the low-power system we're building. Continued...

The Aspire case uses a removable motherboard tray for easy installation. With these compact cases, you can either remove the motherboard tray or remove almost everything else to get to the motherboard section. Aspire chose the tray option.

Once you get the motherboard screwed down, it's time to install the CT-479. The underside of the adapter plugs into the 478-pin socket on the motherboards. Make sure you line the pins up correctly, as the adapter only goes in one way.

Next, install the processor. First, you'll have to set the jumpers on the CT-479 to the correct FSB speed (533MHz in our case). Then you carefully mate the CPU to the adapter socket, making sure to align the pins properly. Finally, you turn a small screw that latches the processor into place.

It all sounds a little klunky, but actually goes together quite well. Just don't forget to connect the 4-pin molex connector to a free 12V connector from the power supply. Note that the heat sink has an independent power connector as well. Continued...

Once the processor is in place, we installed a pair of 512MB, low latency Corsair XMS3200XL modules. Then we added a Sound Blaster Audigy 2 and a BFG GeForce 6800GT OC to the mix. We now have the core of a compact, cool-running gaming system.

One convenient feature of the Aspire case is that the top of the motherboard tray is "tall enough." We've used systems with removable trays that don't actually allow you to install expansion cards because the clearance between the top of the tray and the case is too low to slide in a tray with cards installed. The Aspire case doesn't have the problem.

Once you slide in the tray, you connect up the power cables and front panel connectors (power switch, reset, and so on).

Next, you remove a couple of screws and slide out the hard drive bay, which is actually mounted sideways in the case. After removing the hard drive bay, you can install the optical drive. No rails or spiffy tool-free drive installation is built into this case, however.

You must screw in the optical drive before you re-attach the hard drive bay—otherwise, you can't attach the optical drive mounting screws.

After all the drives are in place and connected, it's time to hook up peripherals and fire it up! Continued...

We took a look at performance across an array of high-end processors from both AMD and Intel, both single- and dual-core.

The hard drives were defragged prior to each major benchmark run. Also, we used the rundll32.exe advapi32.dll,ProcessIdleTasks command to execute and shut down tasks that would normally run during idle cycles.

We ran an extended suite of 32-bit benchmarks:

  • SYSmark 2004, patch 2: a general applications benchmark suite from BAPCo that features a suite of Internet Content Creation tests and another suite of Office Productivity tests.
  • Content Creation: including 3ds max R6, POV-Ray 3.6, After Effects 6.0, Windows Media Encoder 9, DivX 5.2.1 and LightWave 8.0.
  • Synthetic Benchmarks: 3DMark05, version 120 and PCMark04, version 130.
  • Game Benchmarks: Doom3, Painkiller, Microsoft Flight Simulator 2004, Half-Life 2 and Unreal Tournament 2004.

Now let's take a look at how the new processors actually perform.

Overclocking the FX-57
We were able run the FX-57 a full speed grade faster, but it wasn't simply a matter of tweaking the multiplier to 15X. We had to experiment a bit with the voltage as well. The FX-57 would run just fine at 14.5X, but 15X was only stable on the ASUS A8N-SLI at a core voltage of 1.5125V, or 0.1125V above the nominal voltage. This isn't a huge voltage boost, but at these frequencies, we have a little concern as to the long-term effect of running at a higher voltage. After all, this isn't your run-of-the-mill part—it's a CPU that's priced north of $1,000. Killing a $1,000 processor is a bit more traumatic than a $250 one, after all.

Note that we were running with air cooling, but using a Thermalright XP-90 with a Vantec Stealth 92mm fan. That's not a stock cooler, but we also need to note that temperatures never crept above 60 degrees. Voltage seemed to be more of an issue than temperature.

Still, at the higher voltage, the system was rock solid. Unfortunately, we ran out of time, so we didn't get to fool around with memory clocks. It's likely we could have gotten even better performance by juicing the memory up a bit. As it was, we were only able to run a subset of our full test suite at 3.0GHz, due to time constraints: all five games, plus PCMark04 and 3DMark05. Continued...

Let's first take a look at the results from SYSmark 2004, which simulates real-life workloads for both Internet Content Creation and Office Productivity. The content-creation part uses apps like Photoshop, 3ds max, Dreamweaver, and more, while the office-productivity tests use typical office apps, such as PowerPoint, Word, and Excel.

The dual-core Athlon 64 X2 rules the roost here in the Internet Content Creation test, followed by Intel's Pentium Extreme Edition 840. Clearly, dual-core processors have a major impact on content creation, as many of those applications are multithreaded. On the office productivity side, the X2 seems to actually outperform the FX-57, though the Pentium 4 Extreme Edition at 3.73GHz and P4/670 have marginally higher scores than the AMD processors. Continued...

PCMark04 consists of a series of synthetic benchmark suites, each designed to test an individual subsystem, such as memory, processor, and hard drive. The test auto-detects which CPU you're using and loads dynamic libraries optimized for the processor under test for each function. So an Athlon 64 would run code tweaked to run best on its architecture, while a P4 running the same test would run different code optimized for that processor. Many of the tests are small enough to fit into the large L2 caches of modern processors, so those with higher clock speeds have an advantage. It's an idealized view of performance. In the real world, application optimizations can vary widely.

We added the result from running the FX-57 at 3.0GHz here. Note again how well the dual-core processors perform in the PCMark CPU score. Memory scores are a bit different and seem to scale with frequency on both the AMD and Intel line. Of the single processor CPUs, the P4EE at 3.73GHz seems to lead here, while the X2 is out ahead of everyone.

If we drill down to individual memory inspection tests, it appears that the Intel processors perform particularly well in the 4MB block read tests, though they were ahead in most of the block memory tests. However, the AMD processors seem to have a latency edge when running inside the L2 cache. Continued...

Now we turn to performance using actual working applications. We'll take a look at a pair of popular 3D modeling and rendering tools: 3ds max R6 and 8.0. 3ds max performs double duty here, as we run the SPECapc 3ds max test, which tests performance of 3ds max by running model creation, modification, and rendering scripts. Note that we're stuck with R6 for the moment, as the SPEC benchmark hasn't been updated to work with the latest 3ds max release 7. We also perform a pair of pure rendering tests with 3ds max, and run the latest POV-Ray 3.6 benchmark.

The 3ds max SPECapc test is simply owned by the AMD processors. Here, multithreading seems to have less of an impact, as the FX series processors outperform the X2. When we turn to pure rendering under 3ds max, the dual-core processors come into their own, though the Athlon 64 X2 edges out the dual-core Intel Pentium Extreme Edition 840. It's nearly a dead heat between the Intel P4/670 and the FX-57. LightWave 8.0 is a different story, as the AMD processors run away here. NewTek has new rendering benchmark tests with LightWave 8, so we'll likely transition to those in the future. Interestingly, POV-Ray 3.6 runs slightly better on the P4/670 than the FX57. We're looking forward to POV-Ray 3.7, which will add support for multithreading. Continued...

We used Adobe After Effects 6.0, Windows Media Encoder 9, and the latest 5.2.1 release of the DivX codec to perform these tests. We've shifted our WME tests to use the Windows Media 9 advanced profile codec included with Windows Media Player 10. The advanced profile adds more functionality for encoding WMV files, including de-noise, interlaced, and progressive encoding options.

The combination of lower clock frequency and lower memory bandwidth proves to be an insurmountable barrier for the Pentium M. Clearly, its strong suit won't be media processing. Continued...

We use four games plus 3DMark05 to check out game performance. The games include Doom 3, Painkiller (1.6.1 update), Flight Simulator 2004 and Unreal Tournament 2004. All make fairly heavy use of the processor and memory subsystem.

The Pentium M fares poorly in 3DMark05, which is a forward-looking benchmark. However, current generation games fare very well, especially on the Pentium M. The advanced pre-fetching unit, lower cache latencies, and improved x87 floating point all come together to create a system that plays well. Although the Athlon 64 is still a better gaming CPU overall, the Pentium M either matches or outperforms the much higher clock rate Pentium 4 CPUs. Continued...

At first blush, a system built on a $700 CPU that can't keep up with desktop processors in many cases may seem like a losing proposition. But recall that the TDP (thermal design power) of Dothan is 27W, or about 1/4 that of the Pentium 4 model 670 or the Athlon 64 FX-55 or 57. On a per-watt basis, the Pentium M is easily the best performer here.

See more DIY PC systems in our Build It section.

Since we're using a cost effective motherboard solution—the P4P800-VM and CT-479 combo can be had for under $150—the only cost adder is the CPU itself. And you'll end up with a system that uses less power and generates less heat. If you're willing to scale down your graphics card to something less beefy, like a 6600GT or ATI X800 XL AGP, then you have a system that runs cool and offers pretty compelling performance, particularly on games. Even in other applications, the Pentium M is still the power efficiency king.

We're looking forward to testing motherboards based on the Intel mobile 915 chipset, which will likely offer better performance and a richer feature set. But those are likely to be pricier than the ASUS combination using the CT-479 and the aging, but still viable 865G. We managed to build a potent small-form-factor system based on a 27-watt processor. Maybe you should consider this, too.

Product: Intel Pentium M 770 Processor at 2.133GHz
Web site: Intel
Price: $700 check price
Pros: Extremely efficient power usage; cool running; very good game performance.
Cons: Slower than desktop CPUs in some traditional applications; $700 is still a lot for a CPU.
Summary: The Pentium M can be the core of a highly efficient, compact system that generates little heat and outperforms pricier desktop CPUs in some applications.
Rating:

Product: CT-479 Socket 479 Adaptor
Web site: ASUS
Price: $50 check prices
Pros: Easy installation; uses existing technology for running Pentium M processors.
Cons: Only two certified motherboards; no immediate growth to more modern chipsets
Summary: The CT-479 lets you easily add a Pentium M processor to an 865G-based desktop motherboard, allowing you to build a highly efficient system on top of common components.
Rating:

Product: Aspire X-QPack Micro ATX Case
Web site: Aspire
Price: $80 check price
Pros: Low cost; 420W power supply; easy installation.
Cons: Some sharp edges; old style ATX 2.0 power supply; handle seems a little fragile.
Summary: The Aspire X-QPACK is a slick little case for the LAN party set if you have an older ATX 2.0 motherboard.
Rating:


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Loyd Case came to computing by way of physical chemistry. He began modestly on a DEC PDP-11 by learning the intricacies of the TROFF text formatter while working on his master's thesis. After a brief, painful stint as an analytical chemist, he took over a laboratory network at Lockheed in the early 80's and never looked back. His first 'real' computer was an HP 1000 RTE-6/VM system.

In 1988, he figured out that building his own PC was vastly more interesting than buying off-the-shelf systems ad he ditched his aging Compaq portable. The Sony 3.5-inch floppy drive from his first homebrew rig is still running today. Since then, he's done some programming, been a systems engineer for Hewlett-Packard, worked in technical marketing in the workstation biz, and even dabbled in 3-D modeling and Web design during the Web's early years.

Loyd was also bitten by the writing bug at a very early age, and even has dim memories of reading his creative efforts to his third grade class. Later, he wrote for various user group magazines, culminating in a near-career ending incident at his employer when a humor-impaired senior manager took exception at one of his more flippant efforts. In 1994, Loyd took on the task of writing the first roundup of PC graphics cards for Computer Gaming World -- the first ever written specifically for computer gamers. A year later, Mike Weksler, then tech editor at Computer Gaming World, twisted his arm and forced him to start writing CGW's tech column. The gaming world -- and Loyd -- has never quite recovered despite repeated efforts to find a normal job. Now he's busy with the whole fatherhood thing, working hard to turn his two daughters into avid gamers. When he doesn't have his head buried inside a PC, he dabbles in downhill skiing, military history and home theater.
 
 
 
 
 
























 
 
 
 
 
 

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