There is no temperature sensor on the CPU. For those interested about temps this is from a conversation I had with the maker of TempMonitor and contains some VERY GOOD information about the device and temp programs:
Original question:
Okay I just researched and saw that the AK8973 (the device listed on the screen in the OP) is the compass within the phone. So then I'll mod the question as to if they is better (more precise) than the battery temp that other programs read?? Is this closer to the processor or is that just one of the sensors that the monitor reads?? Thanks again.
Answer from DustinMJ (the developer):
This is a very good question, and I'm glad you asked it
First, yes, this is not a sensor located on the actual proc itself. The sensor this app reads from is the primary 'Temperature Sensor' as identified by the android system (The app 'asks' the android system for it's temp sensor). Based on the api docs, the result is a 'composite result', however, the Droid does not appear to have this set up, so no 'default temp sensor' is returned that would allow the app to listen for 'composite results'. When this happens (which it does on Droid), the app will ask for 'all sensors' in the 'temp sensor' category (the droid then returns only one sensor) and tries to use the best option (On droid the one sensor that is returned, is the best option). I can't say for sure, but based on my research and testing, both of these temps come from the same sensor.
Before I go further I want to say that I love the curvefish battery app and have much respect for the developer, I highly recommend this as a supplement, and it's the reason my app does not have a widget.
Here's where things get interesting... there are two ways that it's possible to get *any* temperature reading on this device (well actually there's one more, and I'll touch on that at the end of my spiel), either by using the system to get real-time data, or tapping a readout file that the system stores for battery temperature. The problem with the first option is that it can take a while for the sensor to begin to return data, but once the data is returned, it is real-time data from the sensor. The problem with the second option is that the system doesn't update the file very often at all (Really, at all... I've yet to figure out the exact interval but it's slow... minutes or even halves of hours in between updates, at least on my device), however, there is no delay in reading this data.
The latest version of the TempMonitor app is a 'composite' of these two methods, that is, it shows the data stored by the system while it's waiting for real-time updates from option 1. This is nice because it gives you immediate data, but the data stored by the system could be 15 minutes old... so it's no good for OC, and really can't be trusted as 'current', wait for it to get real-time updates. The notification runs as a completely different thread (it's separate from the main app screen), so once it's on the notification bar, it receives real-time updates indefinitely. This is your most accurate temp reading.
ALWAYS TRUST THE NOTIFICATION TEMP, it is always real-time and reads from the best possible sensor available.
The curvefish battery app reads the temperature that the system stores, at an interval that I'm not sure of. Remember that the temperature is stored at sporadic and lengthy intervals, so this is not the best value to trust when OC'ing. If you doubt this, prove it to yourself:



Code:
Open the current market version of the TempMonitor, and if it doesn't say "Showing system data, waiting for real-time updates", close it, and open it again until it says that (this means the system is not responding good to real-time update request, this tends to happen when you visit the app screen multiple times really quickly). Look at the value shown for the system stored temperature and compare it to the curvefish readout... it may be different, but this is not because it's a different source, but because of the curvefish battery app update interval. To prove this, delete and recreate the curvefish widget on your homescreen.



SensorList (also on the market) reads only the real-time data sent by the system, this is why sometimes it says 0 for a long ass time before it finally updtes.
I'll stop blabbering there, 'cause Brent hates to read long posts

, I hope this was helpful. If you see something I missed or you think is wrong, please call me on it