Noise & Overclocking
For this test we chose a Pentium M 755. Clocked at 2.0 GHz, this processor uses the socket 479 like all other Pentium Ms. The maximum supply current is 1.34V, but it’s also specified to work with 0.988V at 600 MHz. DFI had the great idea of providing a cooling system with the motherboard. This is a good thing because as the holes around the socket form a 41x41 mm square it’s only suited for a chipset or homemade radiator.
A 40mm NMB fan, the 1604KL-04W-B49, lies on the top of the small sized aluminium radiator. The first thing you may want to do is remove the low quality thermal paste to and replace it by real one. The fan has a 12V electrical input, spins at 5500 Rpm and is too noisy for a silent computer. DFI doesn’t provide a funtion to reduce the fan speed according to the CPU temperature, and it isn’t also possible to do it with
SpeedFan either. So you will have to reduce the power supply with an electric tension regulator or for expert users decrease the voltage to 7V by combining the +12V and the +12V to a Molex connector and the mass to a +5V. With 7V, this fan rotating speed is enough for a Pentium M clocked even at 2 GHz. Noise is still noticeable because of the engine, however. If the voltage is reduced to 5V, it is still possible to hear the engine and the rotating speed isn’t enough for a P-M 2 GHz.
In fact, after a bit of research we found that this fan was actually a product found on basic models (of low quality?). We replaced it by a chipset fan ABIT AN7, a simple T&T MW-410M12S. With a 12V electrical input, the fan spins at 5500 Rpm and is quite audible but clearly less than the DFI and a more efficient cooling system. If the voltage is reduced to 7V, it’s still possible to hear (putting your ear directly on the fan), but temperatures are still acceptable even with 5V (2100 Rpm).
Here are temperatures measured under Prime95 with our Pentium M 2.0 GHz at 2.4 GHz.
- NMB / 12 Volts : 42.5°C
- NMB / 7 Volts : 48.5°C
- T&T MW-410M12S / 12V : 39.0°C
- T&T MW-410M12S / 7V : 44.0°C
- T&T MW-410M12S / 5V : 54.0°C
Cooling down a processor with a simple chipset fan and with a low noise level? This surprised us we are used to desktop processors. The SpeedStep, however, doesn’t work initially with all motherboards but there is software
RMClock which makes it possible, adjusting the frequency and input power according to the level of use. This capability is very useful for laptops, because it helps save energy. It’s less useful for desktops especially with processors that can be discreetly and efficiently cooled down.
