Asus M3A78-T: AMD's IGP Gets Another Boost

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FAN CONTROL

For customizable control, SpeedFan is our application of choice. If properly supported, it can be configured to raise/lower multiple fan speeds to designated limits when any specified temperature threshold is breached.


SpeedFan & PC Probe readings.

SpeedFan allows for a high degree of functionality with the M3A78-T. After some experimenting we found that it more or less matches Asus' PC Probe readings, except for the +12V rail. In addition, the sensor that correlated to CPU temperature was 6°C higher than in PC Probe. The sensor labelled "MB" seemed to be tied to the southbridge temperature — when we placed a fan over the southbridge this reading dropped by a few degrees, then increased to its original value when the fan was removed.

Fan control can be enabled for 3 of the 4 fan headers on the board — fans connected to the header labelled PWR_FAN will run at full speed.. Setting PWM modes 1-3 in the Advanced menu from "SmartGuardian" to "Software Controlled" enables three different sets of controls. Speed01 controls the CPU fan header using PWM (its range was 200 to 2500 RPM when a Scythe 92mm PWM fan was connected to it), Speed02 controls the CPU fan header using voltage, and Speed03 controls both the CHA_FAN1 and CHA_FAN2 3-pin headers in unison using voltage. Voltage control is complete, from allowing users to bring fans to a complete stop if desired.

Q-Fan

We tested the board's Q-Fan feature by connecting the fan on the CPU cooler to a variable DC fan controller set to a relatively low 5V and proceeded to stress the processor using CPUBurn. The CPU and Chassis fan speeds were monitored and graphed using SpeedFan.

Q-Fan Behavior
Critera
Silent
Optimal
Perf.
Trigger Temp.
43°C
33°C
28°C
Range of Increase
6°C
6°C
3°C
Min Fan Speed
~60%
~60%
~90%
Max Fan Speed
~100%
~100%
~100%

The "Silent" and "Optimal" settings are pretty much identical except for the trigger temperature which is seperated by 10°C. Both fans run at about 60% speed until the trigger temperature is reached. The fan speeds then increase over the next 6°C until they max out. The "Performance" setting is even more aggressive, with a very high minimum fan speed, low range of increase and low trigger temperature. With the minimum fan speed already at 90%, the "Performance" setting is almost the same as having Q-Fan disabled.

OVERCLOCKING

With effective third party heatsinks and low power CPUs , overclocking, to an extent, can improve performance without compromising the noise level of a silent PC. A simple overclocking investigation was conducted with the CPU multiplier set to 5x and RAM at 533Mhz/2.10V. The CPU frequency was increased in increments of 5Mhz/10Mhz until the system failed a 5 minute run of Prime95 with ATITool 3DView running simultaneously or failed to boot or showed other signs of instability.


The maximum FSB overclock with our X2 4850e.

We found that the board could take a maximum CPU frequency of only 220Mhz and could thus theoretically overclock a capable CPU up to 10% above stock. At 225Mhz and above artifacts appeared in ATITool, and at 250Mhz and above, graphical distortions presented throughout the boot-up process. The nature of the instabilities indicate that the IGP is tolerant of only mild increases in CPU frequency. We should note that further overclocking may be possible by applying greater voltage to the northbridge or southbridge. Overclocking is not one of our main testing criteria; we perform a only cursory out-of-the-box overclocking examination.



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