ABIT NF7-S dumb questions

Okay, roll your eyes, snicker but if you're in the know, please share the wealth.
First dumb question-the Powerfan connection on the MB..is this to monitor the PSU fan speed? I don't want to hook a power source into a power source to find out. This question is probably the most obvious and embarrassing but, but I just don't know dammit. The manual is poorly translated from 'whatever' language and not very clear about such things.
The next question is about temperatures. I want to try my hand at overclocking so I want to know damn well exactly what they are. I have a Hardcano9 with a sensor hooked up under the CPU. I was showing about 3c lower than the motherboard. I had heard that the new BIOS lowers the temp. and I assumed it was to a more accurate reading. I flashed the BIOS and now its reading ridiculously low. Right now its showing 19c with the Hardcano9 sensor showing 34.6c. This can't be right.
One more dumb question is about fan rpm's. I have a Smartfan2 hooked up to an SK7. Going from 'nice 'n quiet' to "roaring" is only a 1c difference?! If this is correct whats all the thread fuss about quieting loud fans if running a screaming monster is only going to drop the temps. 1c? The only thing I can figure is its particular to my setup and maybe there's a wider margin under extreme loads?
Very silly questions but knowledge is power and I have to start somewhere.

1. Yes it's to monitor the fan speed of your PS, or any other fan you hook up there with RPM sensing. My 430W Antec TruePower doesn't have an RPM sensor (usually a yellow cable) in the 2nd fan power connector. AFAIK the 2nd fan will still work even if you don't connect the PS fan to yur mobo. Also, unless you're really stressing your PS, as long as the rear fan works you'll be fine.

2. 19C sounds really low for a CPU, my case might get into the low 20's C in winter, 34C is good for the CPU. Try the windbond utility that came with your mobo.
Which CPU do you have, and what speed are you running it at?? Try running SETI or something else CPU intensive and see what your temps are then.