Cooling Fanbus Temperature Problem(s)

Being a complete git and all, I'm running all of my computer's fans through an NZXT fanbus which runs with it's own temperature probes: http://www.nzxt.com/products/sentry_lx/ Basically, five probes stuck to various heatsinks etc, control five fans, and the problem is the fact that the temperature sensors are leetle beet off.

For example, my CPU, according to CPUID's Hardware monitor, is currently running around 46°C. The Sentry, however, reads only 32°C, and has accordingly set the fan speed at a meagre 1krpm, which isn't helping matters. I'm not worried about it catching fire just yet (it seems impossible to break 50°C with anything but the GPU); but the bus always seems to think it's about 10 degrees colder inside than the computer thinks it is.

tl:dr; Do temperature probes always underestimate? And should I go back to using the motherboard's own plugs?

 

I would use the mobo for the cpu. I have only ever used sensors to monitor areas of the case since I have never been able to afix then close enough to a heat sorce when covered by a heat sink.