Shuttle SN95G5: A64-939 SFF

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The following components were installed in the Shuttle SN95G5:

  • AMD64 3500+ S939 processor (2.2GHz Winchester core, 1 GHz HTT)
  • 2 x 512 mb OCZ DD SDRAM PC3700 Dual Channel Gold
  • Matrox G550 AGP video card
  • Samsung 40G notebook HDD - nestled on soft foam in 3.5" HDD bay.
  • Microsoft Windows XP Pro SP2 fully updated

The Samsung notebook drive is non-standard. This barebones system is designed to accept a standard 3.5" HDD, but in our experience, even the quietest 3.5" desktop HDD makes too much noise, particularly vibration-induced noise, to be recommended for a quiet SFF system. The main issue is placement so close to the user. SFF are meant to be placed on top of the desk, within reach of the user for easy access to the optical drive and front panel ports. In such proximity, it is almost impossible to obtain a level of noise SPCR considers quiet (<30 dBA/1m) without resorting to the very quietest HDD in an elastic suspension.

Samsung notebook HDD nestled in 3.5" bay; top picture from side/back, bottom picture from front.

If our standard recommended quiet Samsung P series 7200 rpm 3.5" HDD was mounted normally in this system, the overall noise level would move up to around 30 dBA/1m or slightly higher. There would also be a level of hum from HDD vibrations that would be too high for us to ignore. This is true of ALL small form factor systems we know of.

This begs the question, "Can a 3.5" HDD be soft-suspended in the Shuttle SN95G5?" The answer: Probably not without modifying the drive cage or eliminating the optical drive to use that space for a suspension. There is simply not enough clearance beneath the HDD cage, which is the place we've been able to suspend 3.5" HDDs in some other SFF PCs.

Very little clearance to suspend a HDD.


A BIOS update was available for the SN95G5 at the Shuttle website. It was dated mid-Dec 2004. It is our general policy to use the most recent BIOS available at the time of testing, so WinBios was downloaded and used to flash the board to the new BIOS.

There are a variety of user-configurable options, including Power Management, which seemed the obvious place to look for a switch for AMD's Cool'n'Quiet technology. The power management options are related to the conventional suspend mode; there are no references to Cool'n'Quiet in the BIOS. It turns out that CnQ is automatically supported by default.

Surely, by now, everyone is aware of Cool'n'Quiet, but for the record, here is a quick summary:

Cool'n'Quiet dynamically varies the CPU clock speed and voltage so that it is not under heavy load, the power draw and heat disspation is minimal, but makes the full power of the CPU available instantly whenever the load goes up. The changes happen so fast, it is impossible to notice when the processor speeds up or slows down. The exact frequencies and voltages of the reduced speed and voltage vary a bit depending on the type of A64 you have. Earlier versions of the A64 went down to 800 MHz @ 1.3V when CnQ kicked in. Newer versions idle at 1000MHz @ 1.1V. The aim is to reduce power consumption and heat when the CPU does not have a demanding load. It is the same technology that has been used for a number of years in both AMD and Intel mobile processors to stretch battery life in laptops, under the names Speed Step and Power Now! Now with CPU thermal management so high on every PC maker's priorities, it makes perfect sense to bring the technology to desktop systems. It was implemented in the very first Athlon 64s AMD brought to market in 2003.

To enable CnQ, one has to have a CnQ supported motherboard, then download and install the CPU driver from AMD's web site and set the Power Option Properties in Windows to Minimal Power Management. There are several versions of the CPU driver, for various operating systems.

It is probably confusing for some users that the term Cool'n'Quiet is used to describe only the Windows ME and Windows 2000 version. The Windows XP version is called AMD Athlon 64 Processor Driver for Windows XP.

The CPU's core voltage had a wide range of settings from as low as 0.800V to as high as 1.700V in 0.025V steps. This allows for some serious manual undervolting, as an alternative to Cool'n'Quiet..

BIOS: CPU Vcore Adjustment.

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