I also have an 8350 and it appears there's something wrong with either the temperature sensor on the die, or, it's being mis-read by almost every temp program. I've seen a few people with this issue, I'm not sure if it's a 100% thing or if it's limited to a select few batches.
For starters, it's nothing to worry about, it makes things a bit of a pain, but what appears to be happening is indeed - an incorrect reading.
To give you an example, idling while typing this post I'm sitting at around 8c in CoreTemp, and the CPU temp monitor in HWmonitor. Every software that takes the temperature from this particular sensor seems to display similar and/or identical readings.
The fluctuation you're witnessing happens also, and it's an extremely quick jump, not enough time for it to be a realistic rise in temperature.
The best solution I have found isn't really a solution at all, but it's to monitor the socket temp as opposed to CPU. This will be the sensor that displays a more realistic level in the mid 20's/ 30's (depending on your case temps and at idle ofcourse). It's not accurate because, especially at higher loads, it's only going to be displaying how warm the socket itself is from that sensor, not the die, generally this means it can be anywhere from a few degrees to 10 or more out.
The CoreTemp software to my knowledge doesn't have or use this sensor, it sticks with the faulty one, but it's still a great bit of software to keep for monitoring the current load levels. HWmonitor will display both. SpeedFan is dependant on setup, and the motherboard will use the socket temp sensor but the figure will be a little higher because, while in the bios, Cool n' Quiet isn't functioning, therefore the processor will be at its stock clock of 4GHz.
Also, yay for first post :3
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