This is the main part of SpeedFan. Most of the time you will look at this page. Another page of interest would be the one related to hard disk S.M.A.R.T. values.

According to your hardware, on this page you will see:

CPU usage		If everything works fine, you will see here as many bars as many CPUs you've got. Each bar shows the CPU usage for each CPU. On my dual processor board, I can see 2 bars.
Fan RPMs		Fan RPMs (revolutions per minute) are shown here. If you read 0, it might be due to too small a FAN DIVISOR. You can enter configuration dialog, on the ADVANCED tab and check to see if for your hardware monitoring chip SpeedFan support changing its setting. If it is supported, you might try setting it to a higher value (8 should do the trick for slow fans). Please note that when you slow down fans by using SpeedFan's capabilities, reported RPMs might be odd. Usually you'll get very high reported speeds. This is mostly due to the fact that fan speeds changes are achieved by lowering the voltage sent to the fan itself. Most hardware monitoring chips do this voltage lowering by using PWM (Pulse Width Modulation). In poor terms, PWM means that the usual voltage is not always sent to the fan, but it is quickly turned on and off, thus simulating the effect of a lower voltage. This ON/OFF transition will cause the fan to improperly report its speed. Every fan reacts in a different way. Consider that SpeedFan never relies on reported fan speeds when controlling them. Only temperatures are relevant and SpeedFan will lose no functionality even if you've got a two-wired fan that doesn't report its speed.
Temperatures		Here you will find all the temperature readings that SpeedFan could detect. These include those from the hard disk (if it supports this feature) and from ghost sensors. Ghost sensors are those that either are improperly detected by SpeedFan or disconnected (not actually used by the motherboard to monitor anything). You can go to the TEMPERATURES tab in the configuration dialog and hide those temperatures you're not interested in. Several users ask why I didn't show more self-explanatory names for each temperature. The problem is that I don't know which temperature each motherboard manufacturer actually connected to what :-( As a rule of thumb, the higher (realistic) temperature is the CPU and the lower (realistic) one is from your CASE. CPU temperature can be recognized even because it's the one that rises faster when CPU usage is at full load for a few minutes.
Fan SPEEDS		Here you can (try to) set a lower speed for your fans. You will find something here only if your hardware supports this feature. Please note that both your hardware monitoring chip must support it and your motherboard must include the needed circuitry. Several motherboards seem not to include this circuitry, even if their hardware monitoring chip (and, thus, SpeedFan) would be able to change fan speeds. The first test you should consider trying (please read my considerations about fan speed changing) is setting each speed to 0%. If any fan stops (you should listen to it :-)) then you're on the right way. Try raising that percentage and try to understand if the speed can be smoothly changed. Do not rely on reported fan speeds, but "listen" to the sound :-) If your motherboard can change fan speeds and it's not listed on my supported hardware web page, please let me know and tell me if you can change fan speeds, smoothly and if you can stop fans :-)
Voltages		Here you can find detected voltages. Once again, the datasheets for those hardware monitoring chips report reference circuitries to be used, but several motherboard manufacturers use different ones. SpeedFan shows voltages' names expected according to each datasheet. If they are different for your motherboard, feel free to use the VOLTAGES tab in the configuration dialog to change names.