Pentium M for the Desktop: AOpen i855GMEm-LFS & DFI 855GME-MGF

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We will build a couple of test systems and run some basic benchmarks and examine in detail the thermal performance of these Pentium M systems. We will also experiment with various configurations to answer some burning questions:

  • Just how cool does a 21W CPU run?
  • How much current does a Pentium M system draw under full load?
  • How well do the default cooling systems work and are they quiet enough?
  • Will the stock coolers work well enough to be run passively?
  • Will third-party cooling solutions be more efficient than the default coolers?
  • Will third-party cooling solutions allow the CPU to be passively cooled?

Since the Pentium M CPU runs so cool, we're going to utilize the quietest hardware available. If our goal is to build a fast and extremely quiet system, the ancillary hardware shouldn't drown out the CPU cooler. Our test system will be based on the following hardware, all of which is ridiculously quiet:


The test platform is an open system not enclosed in a case.

Intel Pentium M 755 - 2.0GHz Dothan core - TDP is 21W, MP is 26.8W.
Sapphire ATI Radeon 9600Pro passively cooled video card (AGP)
Mushkin PC3200 Level II - 2 x 512MB DDRAM @ 2-2-2-5, 333MHz
Samsung MP0402H 2.5" 5400rpm, 8MB cache notebook hard drive, decoupled with Sorbothane blocks (<17 dBA/1m)
Seasonic Super Silencer 300W (rev A1) PSU modded with 5V Panaflo M1A (<18 dBA/1m)
Arctic Silver Ceramique Thermal Compound
Two-level metal platform with rubber damping feet. Motherboard on top; other components below.
CPUBurn processor stress software
Motherboard Monitor software to track CPU temperature and fan speed
Seasonic Power Angel power monitor used to measure system power usage

Pentium M test platform. Note the 2.5" notebook drive on top of the FDD.

Each motherboard was tested using the same components. Only the board and the various heatsinks changed.

Due to the DFI CPU cooling setup, we were not able to use typical aftermarket CPU cooling hardware. Much of the DFI testing was done with the stock heatsink. Prior to all testing, the heatsink was installed as per the manufacturer's and Arctic Silver's instructions. No benchmarks or thermal tests were run until system stability was assured by running the Prime95 Torture Test (v23.8) for 8 hours and Memtest86 (v3.20) for at least 24 hours.

Each thermal test was run for 30 minutes even though temperatures generally stabilized within 15 to 20 minutes. Each test was repeated three times on consecutive mornings to check consistency. All results were within 1-2°C of each other and the average readings are included in the charts.

No tests were run unless the ambient temperature was at the reference level of 71°F (21°C)

* All temperatures in degrees Celsius.
* Diode: Reading from Pentium M 755 CPU diode via Motherboard Monitor. Diode was calibrated on each board using the standard SPCR CPU Diode Calibration method.
* Temp Rise refers to the difference between ambient temperature and the diode reading. .
* °C/W refers to the °C rise per watt of heat dissipated by the CPU.


The systems were easily assembled as each motherboard uses standard components laid out in the usual "ATX" style. The low profile mPGA479 ZIF socket was a pleasure to use. I found the camming action of rotating a little screw 180° easier than using the typical locking lever.

The Pentium M is the first CPU without an integrated heat spreader that I've used in years. So it was with some trepidation that I installed the AOpen heatsink for the first time. I flashed back to my AMD Thunderbird days and listened carefully for that stomach churning cracking sound as I put pressure on the heatsink, but everything went just fine. The DFI heatsink was even easier to mount, due to the no-fuss springloaded screws.

This comment is relevant mostly for reviewers, but... One nice thing about the small, exposed core of the Pentium M: It takes just a tiny bit of thermal interface goop to cover the CPU core, which is also faster and easier to clean compared to an integrated heatspreader. This was a consideration during the extended testing of these boards. It seemed like I was swapping the motherboards every time the wind changed directions.

Both builds went perfectly with each system reaching POST on the first boot. I flashed the BIOS of each board to the latest revision and then installed Windows XP sp2. After Windows was installed I loaded the latest Intel chipset drivers and then installed the NIC drivers from the supplied driver disk. Once connected to the web, all the Microsoft OS updates were installed. Then, a minor amount of GUI configuration, and on to the benchmarks.

Each system in stock configuration. AOpen on top, DFI on bottom. Notice difference in heatsink size.

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