BlueSmoke - Review : Senfu Digital Thermometer

BlueSmoke - Review : Senfu Digital Thermometer

Date : Aug 25th, 2001

Category : Cooling

Manufacturer : Senfu

Author : Jin-Wei Tioh

Temperature monitoring is important, not only in industrial settings, but in your computer as well. This is especially true given the rise of overclocking, which results in drastically increased CPU operating temperatures. Increasing amounts of heat are also generated by other components within the system. With the plunging costs of high RPM HDDs, CD-R/W drives, and the advent of literally hot graphics accelerators, heat management becomes a critical issue.

All computer components have a operating temperature range. Obviously, we're not concerned with the lower limits (unless you live in Alaska, that is). However, exceed the upper limits, and at best, the lifespan of a particular component is shortened. At worst, the consequences can be downright disastrous. So how do you know what temperature your components are running at?

In the case of CPUs, the CPU core temperature is probably the most important parameter. Intel processors since the Pentium II all incorporate a thermal diode in the core, which in conjunction with some minor system monitoring hardware on the motherboard, is able to give you core temperature readings via some system monitoring software. However, AMD processors lack this feature, thus being completely dependant on the motherboard to supply thermal probes to monitor the processor temperature, usually via a thermistor in the middle of the socket.

In addition to this, some motherboards support an "external" thermistor, like the old ABIT BX6 Rev 2, which you can use to monitor the surface temperature of whichever component that you fancy. So, you CPU and let's say your intake air temperature are covered. But what about your HDD, graphics card, etc? That's where Senfu steps in with their digital thermometer, kindly supplied by Scott Brown of HighSpeeed PC.

The Senfu comes in a small box, measuring roughly 7.0 x 5.5 x 5.5cm (HWD). Inside, you will find the main module containing all the necessary electronics, with the thermal probe attached by a 1m long cable, and a small L-shaped plastic stand. The main module is packaged in bubble-wrap to minimize damage to the LCD screen and plastic housing.

Senfu Digital Thermometer Specifications
Range	-40°C ~ 90°C
Resolution	0.1°C (max 0.3°C)
Accuracy	1°C (-40°C ~ 90°C)
Display	Constant Display
Sampling	3 seconds
Battery	G10 x 1
Probe	1M Long or Buyer's option
Color	White / Black Buyer's option

The Senfu is powered by a G10 battery, a button-sized mercury-oxide power cell. Its 1m long cable does show that the manufacturer is considerate, seeing that some users do have very tall cases. The LCD screen is more than adequate, with the temperature readings being readable at long distances.

Due to its small size, it fits snugly (height-wise) in an external 3.5" drive bay. You can cut a hole in your casing to fit the unit, or snap it in the included plastic stand and place in on top of your casing. Personally, I haven't thought of how and where to stick the Senfu on my SuperMicro SC-750A, but meanwhile, you can visit our case gallery for some ideas.

So, how is the Senfu's temperature monitoring? It displays the temperatures in degrees Celcius, with a sampling rate of 1/3Hz. With some modifications, it can be converted to give readings in degrees Fahrenheit. As mentioned earlier, the Senfu has a monitoring range of -40°C to 90°C, which more than adequately covers the operating temperature range of even peltiers. If the temperature is goes below -40°C, 'LLL' will be displayed. Likewise, if the temperature goes above 90°C, it will display 'HHH'. Senfu claims an accuracy of 1°C, a little boastful, but its readings didn't stray too far from that of a complicated and expensive laboratory thermo-coupler.

Monitoring temperatures via the Senfu definitely has advantages over more conventional means. For starters, you don't have to start a potentially resource hogging program just to get a temperature reading. This does have some plusses, as you can get updated temperature readings regardless of what applications you're using. The Senfu's wide temperature range also means that it is suitable for use with any cooling solutions, eg. peltiers, water coolers, or conventional heatsink/fan combos.

Everything is not rosy however. Unless it is modified, the Senfu will only display temperatures in degrees Celcius, something which we'll show you how remedy in another article. Another peeve is the lack of an ON/OFF button. The only way to turn off the probe is to remove the battery, something us silicon couch potatoes will find tedious to do. Thus, you may find yourself having to replace the battery sooner rather than later. This could have been alleviated with a Molex connector, which would allow the Senfu to tap power directly from your PC's power supply, a virtually unlimited power source. I'm currently testing/designing a mod which will allow you to do just that, so stay tuned.

With a price of just US$14.50, the Senfu is a might expensive, but you do get what you pay for, namely accurate and reliable temperature measurement. In fact, I've just ordered another 2 of these babies for use with our heatsink testing methodology. This is definitely one toy that you would not want to miss out on. So head on over to HighSpeed PC's online store and go get some!
Highly recommended!