**Official e8400/e8500 Retail OC Thread

[unclewebb]

There seems to be the usual amount of confusion about temperatures so here's another way to directly access the data from within the Intel CPU.

Start up CPU-Z and go to the About tab and click on the Registers Dump (.txt) button.
Save this file, open it and scroll down to the model specific registers for each of your cores.



MSR 0x0000019C contains the only Intel documented temperature data for these processors. By looking in here you are reading the digital thermal sensors (DTS) directly. Bits [22..16] are located in the third and fourth digit. In my example that is 0x3F hexadecimal which equals 63 decimal.

If you are mathematically challenged then fire up Calc or head to Google and type in:
0x3F in decimal
and it will do the conversion for you.

This shows that my Core0, at idle, is 63 degrees away from TjMax or its safe maximum operating temperature.

I am using an older E6400 which has a TjMax = 85C so CoreTemp reads the DTS data and then calculates that my absolute temperature is 63C degrees away from 85C so it reports an idle temperature of 22C (85C - 63C). CoreTemp is using TjMax = 105C for the new 8x00 series processors.

Intel neither publicly documents that these on chip sensors are accurate for low idle temperatures or provides any public documentation stating what TjMax actually is. It only documents that these sensors are used for thermal throttling and ultimately for thermal shut down if needed.

When your processor heats up the DTS will decrease. When the DTS approaches zero you will begin to slow down due to thermal throttling kicking in but most people are miles away from that ever happening. As long as you always have some headroom as reported by the DTS and your computer is stable at full Prime load then there is no reason to be too worried about your absolute temperature. It is just a number and you are operating within the Intel temperature spec for these chips. At 4+ GHz you might be a little over on that spec but that's a secret that Intel doesn't need to know.

You can also start CoreTemp and go into the Options->Settings menu item and turn on Show Delta to Tjunction max temp.
This setting also reads the DTS data directly and should exactly correspond with the above DTS data that CPU-Z prints out.

[Merc14]

There seems to be the usual amount of confusion about temperatures so here's another way to directly access the data from within the Intel CPU.

Start up CPU-Z and go to the About tab and click on the Registers Dump (.txt) button.
Save this file, open it and scroll down to the model specific registers for each of your cores.



MSR 0x0000019C contains the only Intel documented temperature data for these processors. By looking in here you are reading the digital thermal sensors (DTS) directly. Bits [22..16] are located in the third and fourth digit. In my example that is 0x3F hexadecimal which equals 63 decimal.

If you are mathematically challenged then fire up Calc or head to Google and type in:
0x3F in decimal
and it will do the conversion for you.

This shows that my Core0, at idle, is 63 degrees away from TjMax or its safe maximum operating temperature.

I am using an older E6400 which has a TjMax = 85C so CoreTemp reads the DTS data and then calculates that my absolute temperature is 63C degrees away from 85C so it reports an idle temperature of 22C (85C - 63C). CoreTemp is using TjMax = 105C for the new 8x00 series processors.

Intel neither publicly documents that these on chip sensors are accurate for low idle temperatures or provides any public documentation stating what TjMax actually is. It only documents that these sensors are used for thermal throttling and ultimately for thermal shut down if needed.

When your processor heats up the DTS will decrease. When the DTS approaches zero you will begin to slow down due to thermal throttling kicking in but most people are miles away from that ever happening. As long as you always have some headroom as reported by the DTS and your computer is stable at full Prime load then there is no reason to be too worried about your absolute temperature. It is just a number and you are operating within the Intel temperature spec for these chips. At 4+ GHz you might be a little over on that spec but that's a secret that Intel doesn't need to know.

You can also start CoreTemp and go into the Options->Settings menu item and turn on Show Delta to Tjunction max temp.
This setting also reads the DTS data directly and should exactly correspond with the above DTS data that CPU-Z prints out.

Unclewebb-
Thanks for the info. Very well written and understandable. It is the idle temps that I was concerned about as the peak temps seem low for the stress I was putting the chip under. I'd come to the same conclusion that the chip is a keeper since I had a long way to go before i got anywhere near Tj. I'll now not worry so much about the idle temps thanks to you.

[dinos22]

There seems to be the usual amount of confusion about temperatures so here's another way to directly access the data from within the Intel CPU.

Start up CPU-Z and go to the About tab and click on the Registers Dump (.txt) button.
Save this file, open it and scroll down to the model specific registers for each of your cores.



MSR 0x0000019C contains the only Intel documented temperature data for these processors. By looking in here you are reading the digital thermal sensors (DTS) directly. Bits [22..16] are located in the third and fourth digit. In my example that is 0x3F hexadecimal which equals 63 decimal.

If you are mathematically challenged then fire up Calc or head to Google and type in:
0x3F in decimal
and it will do the conversion for you.

This shows that my Core0, at idle, is 63 degrees away from TjMax or its safe maximum operating temperature.

I am using an older E6400 which has a TjMax = 85C so CoreTemp reads the DTS data and then calculates that my absolute temperature is 63C degrees away from 85C so it reports an idle temperature of 22C (85C - 63C). CoreTemp is using TjMax = 105C for the new 8x00 series processors.

Intel neither publicly documents that these on chip sensors are accurate for low idle temperatures or provides any public documentation stating what TjMax actually is. It only documents that these sensors are used for thermal throttling and ultimately for thermal shut down if needed.

When your processor heats up the DTS will decrease. When the DTS approaches zero you will begin to slow down due to thermal throttling kicking in but most people are miles away from that ever happening. As long as you always have some headroom as reported by the DTS and your computer is stable at full Prime load then there is no reason to be too worried about your absolute temperature. It is just a number and you are operating within the Intel temperature spec for these chips. At 4+ GHz you might be a little over on that spec but that's a secret that Intel doesn't need to know.

You can also start CoreTemp and go into the Options->Settings menu item and turn on Show Delta to Tjunction max temp.
This setting also reads the DTS data directly and should exactly correspond with the above DTS data that CPU-Z prints out.

nice explanation there

check out what i also found in that CPUz dump
(btw 0x34 was the corresponding value as per your explanation which is also mentioned in my screen under Core0)

[necron66]

nice explanation there

check out what i also found in that CPUz dump
(btw 0x34 was the corresponding value as per your explanation which is also mentioned in my screen under Core0)

http://img82.imageshack.us/img82/598...board01xw8.png

Mine reads same as core temp

Hardware monitor
-----------------------------------------------------

Intel Core 2 Duo E8400 hardware monitor

Temperature sensor 0	42°C (107°F) [0x3F] (core #0)
Temperature sensor 1	46°C (114°F) [0x3B] (core #1)

Dump hardware monitor

but it never moves from here at idle, only when I load it up.