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The following components were installed in the Shuttle SB81P:
- Intel 520 processor (P4-2.8 Prescott, 1Mb cache, 800 MHz FSB in 775
casing), review loan from Newegg.com
- Samsung SM-352B Combo Drive (CD-RW + DVD-ROM)
- 256 MB DDRAM - PC2700 generic
- Seagate Barracuda IV - now out of date, but still a quiet reference
- Microsoft Windows XP Pro SP2 was installed, along with the multi-megs
of updates ad nauseum.
*A note on the Intel 520 processor: Any Prescott-core P4 in a SFF
PC is a challenge if you're seeking low noise as a primary goal; they run
so very hot that it's hard to cool them in tight spaces without significant
airflow. Intel announced several
months ago that they were expanding the range of 775 CPUs downward to
include lower clock speed Northwood P4s in the mix. We made a special request
to Newegg.com to locate one of these for us, but they were unsuccessful.
For the record, the 520 is spec'd by Intel for a Thermal Design Power of
84W (and a calculated
Maximum Power of 100W), and a maximum casing temperature of 67°C.
You'll note that no video card is listed. Alas, a PCI Express VGA card was
not on hand when we were doing our testing, so the integrated VGA was used.
Suffice it to say that the noise level of the system cannot be any lower than
we recorded here in the absence an outboard VGA card. The only way the baseline
noise level can be lowered is by using a quiet notebook drive. However, this
noise reduction will be mostly obscured by other sources of noise in the system.
We doubt that using a notebook drive in this system would actually improve noise
levels by more than ~2 dBA/1m.
The hard drive was installed in the bottom of the drive cage. The secondary
drive mounts were not tested.
The SB81P has a good range of user options in the the BIOS.
- FSB: 100-355 MHz, in 1 MHz increments
- CPU Voltage: 0.8250-1.5875V in 0.025V increments
- DDR Voltage: 2.70-2.90V in 0.1V increments
- Chipset Voltage: 1.60-1.80V in 0.1V increments
The low point for all voltages...
...and the high point.
FSB adjustment range is 100-355 MHz.
We are happy to see that the BIOS allows both underclocking and
undervolting to levels well below what is actually achievable. These are particularly
important features in a SFF system that may be more of a challenge to silence
because of its small stature and its many proprietary parts.
The SB81P allows PWM-regulated control of the CPU and System fans. Each of
these categories contains two fans, an intake and an exhaust for the CPU category,
and the two 60mm exhaust fans for the System category. The power supply fan
is not controllable from the BIOS, and no RPM measurement was shown for it.
Although the CPU fans must be adjusted together, they do not ramp up at the
same rate. For most of our testing, the intake fan stayed about 800 RPM slower
than the exhaust fan. On the other hand, the system fans are never adjusted
independently; they are powered from the same fan header and do not report individual
Each category can be adjusted between 30% and 100% in 10% increments. Control
is achieved though PWM, not straight voltage attenuation. There is also a Smart
Fan setting that spins the fans even slower than the 30% setting at idle. All
testing was done in Smart Fan mode.
A certain amount of control can be had over the Smart Fan mode via a setting
called "CPU Temp Tag". This allows the user to set the CPU temperature
at which Smart Fan begins to increase the fans speed. Temp Tag is adjustable
between 30°C and 80°C in single degree increments. Since Intel CPUs
start throttling at around the 70°C mark, it is actually possible to set
the Temp Tag to a temperature that should never be reached. In theory, this
means that adventurous users could depend entirely on Intel's CPU throttling
technology to cool the CPU without allowing the fans to ramp up.
Fan speeds can be adjusted to a set level between 30% and 100%, or set
to "Smart Fan" to allow the BIOS to handle it.
It is possible to set the CPU temperature when Smart Fan kicks in.
One downside of having such powerful fan control in the BIOS is that fan speeds
were not controllable via SpeedFan 4.19 in Windows. Aside from this minor
gripe, however, we were fairly pleased with the range of adjustment allowed
by the SB81P.
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