I am confused about temperature readings I am getting from my CPU. I know that there is an entire guide posted related to the subject, but my problem is in my inconsistent readings. My BIOS typically shows my CPU at 36c. idling. Nvidia NTune shows my CPU temperature at around 32c. idling. Core Temp shows my core temps at 47c. and 50c. while idling...a huge difference. My CPU is an Intel E8400 @ 3.6ghz/1600fsb on a XFX 780i SLI board....OC'd obviously. I am running an Arctic Cooling Freezer 7 Pro in a well ventilated Thermaltake Armor case. Do I have anything to worry about? Any information would be appreciated

It depends. How high is your voltage? How much time does your cpu stay @ 100% load?
If the answer is "lots", yes you have something to worry about.
If you dont really need that oc, dial it back a little.
Intel needs to let your mobo know what the tjunction is for your chip. Without that piece of info, you can not know what temp your chip is at.
There are a lot of people being very careful with your chip because the HK/MG is still a bit of an unknown. There is the potential for a "SNDS" type problem.
If 3.6 is the max speed you can get prime stable, I would suggest you dial it back 100 or 200mhz.

Okay. I'm back. As far as the voltages go, I manually set my CPU voltage to 1.25V, my FSB voltage to 1.2V, my memory voltage to 1.85V (4-4-4-12 timings), SPP to 1.4V, MCP to 1.5V, and SPP<--->MCP to 1.2V. The voltages I set did not seem that high compared to the auto settings in my BIOS. With auto on and the OC changes the voltages were set to 1.31V for the CPU, 1.3V for the FSB, and the other settings were the same due to no changes being made by me. MY CPU rarely sees 100% usage although I really haven't stressed out my system with Prime or anything. Since my post, I have set the CPU and FSB to stock speeds, but I have left the memory timings alone at 4-4-4-12 which is what the RAM is rated at anyway. I am a bit of a novice when it comes to overclocking and I can use all the information and assistance anybody is willing to provide. Thanks endyen, perhaps I should try running Prime to check stability.

There are 3... sensors on your C2D chip.

One is the Tcase, bios and speedfan or your MB temp app will read this sensor. It is basically between the 2 cores or more like the IHS temp. This will give you a typically lower temp.

The other 2 are on the cores (DTS sensors) themselves, which will give you a hotter/higher reading.

Also Speedfan will show a CPU temp, then also Core temps. Now if you know what the max Tjuction is, then you should know how to offset the temp readings for the cores. If your CPU has a Tjunction temp of 100C, SpeedFan's (4.33 version) core readings will be 15C off, because it thinks the Tj max is 85C, for an example.

Themal spec's that you may get from Intel, example 72C would be the max temp on the Tcase sensor. The max Tjuction would be for the cores.

I really appreciate the help. It's starting to make a little bit more sense now. Okay, I just ran Prime95 using the stock CPU and FSB speeds for about 3 hours. My core temps were running about 63c. and 60c. according to Core Temp. The other temp, Tcase from what I understand now, was at 47c. The Tj max according to Core Temp is 105c. Correct me if I am wrong, but from what I understand my temps are relatively normal. If I start to see the core temps, after stressing them out, in the 75c.-85c. range I should begin to worry.

I hope I am understanding this correctly.

Yes. I hope it makes more sense now, especially when you fall back an read the guide, and just compare the temps with the CPU that your using to get a better idea to where your temps fall within good thermal spec's.

Even PM CompuTronix, I'm sure he'll be able to help you that way with any other specific questions.

edit:

Scale 2: Duo
E8x00: Tcase Max 72c, C0 Stepping, Tjunction Max 105c, Vcore Default 1.250, TDP 65w, Delta 15c
E8x90: Tcase Max 72c, C0 Stepping, Tjunction Max 105c, Vcore Default 1.250, TDP 65w, Delta 15c

-Tcase/Tjunction-
--70--/--85--85-- Hot
--65--/--80--80-- Warm
--60--/--75--75-- Safe
|---------------------------So your somewhere there 47/--63 -kinda below safe (I guess you could say).
--25--/--40--40-- Cool

Thank you very much for the help....I feel a lot better now. I guess now I can kind of see how far I can push the processor with overclocking since I have a better understanding of the temps. I don't really want to overdo it either. I think 3.6ghz or so is my limit.

Thanks again!