E8400 temp readings

[Reynardin]

what RealTemp settings do you guys use with an E8400?

 

[J-Man]

Default.

 

[Reynardin]

what kind of temps do you get? (temps and distance from TJ max please)

 

[moocow0463]

95c tj max, idles 40c, load tests at 51c, however my bios reads idle at 32c, and ive gone from the stock 3.0ghz to 3.6ghz with no temp changes

 

[Jeno]

95c tj max, idles 40c, load tests at 51c, however my bios reads idle at 32c, and ive gone from the stock 3.0ghz to 3.6ghz with no temp changes

WOW!! that's some extreme temps you got there!!
my e8400 is idling @ 15C and gets to 20-25C on load.

 

[Reynardin]

WOW!! that's some extreme temps you got there!!
my e8400 is idling @ 15C and gets to 20-25C on load.

I generally get 38-40C idle and 48-52 under load.
Jeno, what kind of cooling do you use, and what TJmax / calibration do you use?

Bit hard to get under 30C when that's the ambient temp in my house right now..

 

[moocow0463]

i go off the bios temps, as the bios is usually the most accurate, so i really dont think my 8400 is that hot, there is a page on another forum with how the new wofldales are giving wrong accusations with temp programs, some people are reading over 70c at idle but in bios only in the 30's

 

[Reynardin]

my bios reads the same =/

 

[erocker]

WOW!! that's some extreme temps you got there!!
my e8400 is idling @ 15C and gets to 20-25C on load.

Unless you are using a uber water coolng system or better, your temps are wrong. I would add 20c to your temperatures.

 

[moocow0463]

ya if your bios are the same as real temp readings then id say they are correct, ambient air play a big role on the cpu temps as well, my room temp is pretty warm as well so its hard to lower cpu temps

 

[Jeno]

ill check my bios but i think there cinda accurate, i have jsut been playing cod4 for a few hours and its now doing 21C.

the reason is my room temp i think, this morning it was like 12 fu@k!ing degrees in here, dam this cold winter >:#

ill set vcore to 100v !!!!!

a fire will warm this place up a little

 

[erocker]

If it's 12c in your room the temps could be correct. With a good air cooler the E8400 runs about 27-32c at 72F.

 

[Jeno]

only stock cooling for me :shadedshu

 

[Reynardin]

only stock cooling for me :shadedshu

Where do you live!!?? I want to move there! It's like 30C where I live right now... Summer ftl.

 

[Jeno]

i live in australia.
i get 40C days when its summer down here.

btw i did check my bios and its 2C hotter there

 

[Reynardin]

i live in australia.
i get 40C days when its summer down here.

btw i did check my bios and its 2C hotter there

aaaaaaah no wonder, do you know what kinda temps your computer gets in THAT kinda heat?

 

[Dr. Spankenstein]

unclewebb (the creator of RealTemp) suggests you calibrate the program via a simple process outlined http://www.techpowerup.com/realtemp/docs.php.

 

[rge]

Yep, you can calibrate to get accurate idle temps.

Load temps from around 60-65C on up will be accurately reported by Real temp with tjmax 95 on E8400, without a need for calibration, as DTS output is linear in that range, ie 1 unit = 1C.

No software program will give accurate idle core temps on E8400 (or on most other cpus unless just by luck), because DTS (sensor output) on cpu is nonlinear in that range, and temps read anywhere from 5 to 20C too high at idle on E8400, depending on how nonlinear your uncalibrated diode is at the low range. So if you want accurate idle temps, like Dr. Spankenstein alluded to, you have to use the negative calibration in realtemp. Basically involves setting your cpu to 6x200 or 6x300, vcore to 1.05 to 1.1, keeping at idle, at that point die temp should be 3-4C above ambient, and just adjust idle calibration til there. Or for that matter, use lowest vcore at stock setting with speedstep enabled, and again set core temps to 3-4C above ambient.

Without calibration, most will have accurate temps from 60-65C on. (some may be accurate even at 50C, others not til 70C....as nonlinearity is variable cpu to cpu)

With calibration, you can have accurate across range, or close to it, or you can just ignore or accept the 5-20C too high idle temps, knowing your load temps are still accurate...assuming your load temps put you up to 60C in accurate range. Note, if you do the calibration, it will not affect load temps past 65C, where they are already accurate.

 

[rge]

oops double post

 

[alias_1ab]

my 8400 temps are reading out at 43-44 C idle up to around 60 C while running maximum heat stress test with prime95. using RealTemp 2.60 to get these readings. The Nvidia ESA Tool software that came out a few months ago is neat but its temperture readings are all 10 C above from what RealTemp shows. im using the stock HSF, have the fan speed set to smartfan, the room temp is about 79F (outside its 95F +), and no overclocking of any sort.
my initial thoughts were these temp readings were fairly high considering the E6600 i passed from this machine to another used to give me temp readings in the upper 30's. but after doing so online research, it seems many people are reporting idle temps of near 50 C for the E8400.
also someone mentioned that the temp reading in the bios is the most accurate. i would very much disagree with that assumption. my bios temp reads 61-62C. my antec 160 case has a temp probe which i slid under at the edge in between the hsf unit and cpu itself. it reads 37-38C basically from the surface edge of the cpu. more reason to believe that RealTemp is giving the most accurate temp readings for the E8400.

 

[moocow0463]

http://www.xtremesystems.org/forums/showpost.php?p=2763280&postcount=1259

you need to read through a little bit of the stuff before he gets to the 8400 chips but heres his quotes:

"My E8400 is different. I've seen some users reporting maximum CoreTemps of 70C. When CoreTemp reports 70C for my E8400, the IR gun is only showing an actual temperature of 60C. At lower temperatures the difference approaches 15C. I think this will make a lot of sense for anyone that has gone from dual core Conroe to dual core Penryn on the same board.

The other test I did was I ran my E6400 and E8400 at the same MHz and core voltage. With a small hand held high speed fan pointing at the cores, the lowest I could get down to with my E6400 was 47C as reported by CoreTemp and the IR gun. The 45nm E8400 is smaller and more efficient so common sense says it should run cooler. CoreTemp was reporting 57C during this test but the IR gun was only showing 42C. 5C cooler makes logical sense. Penryn running 10C hotter than Conroe at idle makes no sense.

From this I would have to say to take the absolute reported temperatures based on the on chip sensors with a grain of salt. Intel does not document these sensors being used for that purpose. All of the chips may have a similar temperature curve to what I found but there is no guarantee of that. The on chip DTS was designed for thermal throttling and for showing distance to the throttling point which CoreTemp reports correctly. Just keep in mind that 50 units of headroom until throttling does not exactly translate to 50C of headroom."

 

[rge]

delta to tjmax is always the most accurate way.

But load temps (30 to 35 from tjmax where intel states is linear and 1C=1unit), there is hope for absolute accuracy using tjmax of 95 ie real temp. (or use coretemp and change tjmax to 95)

PIC: IR to my cpu says 74.4C, Realtemp reading 74C. This is at idle, undervolted, underclocked with no heatsink where there is less than 1C gradient from core to casing, and IR approximates core temperature.

 

[moocow0463]

ok so going of tjmax 1c=1unit, 95= 95C, i dont think any computer should run at 95c im sorry, highest temp rating on an e8400 is 72.4C, if you let Distance tj max reach 0 in real temp your processor would be at 95c, unless im mis understanding?

 

[Reynardin]

ok so going of tjmax 1c=1unit, 95= 95C, i dont think any computer should run at 95c im sorry, highest temp rating on an e8400 is 72.4C, if you let Distance tj max reach 0 in real temp your processor would be at 95c, unless im mis understanding?

Wrong, that is Tc max, not Tj max. They are two different things. I'm quite sure that the e8400 CAN detect temps above 74.2 C, as my computer is set to shut off at 85C. In addition, the documentation for the e8400 states that 72.4 is the Tc max, even though it is listed in the Tj max column.

You are correct that no computer should run at 95 C, but it is possible for it to detect temps of up to that. Think, it has to be able to detect a temperature to make judgments off of it, so it makes no sense that it would have a max detection of 72.4, as some computers WILL run at that temp on a hot day.

 

[rge]

moocow, as Reynardin pointed out, 72.4C is for Tcase max, not Tjmax. Tjmax is die temp, Tcase is IHS/outer casing temp.

At idle, undervolted, underclocked state, which is how I do my temperature testing, the two temps, die and case are within 1C. Temp difference between two, or gradient = TDP*theta or 4W*.35c/w or roughly 1.2C. Will actually be less than 1C with no heatink on.

However at load with heatsink on, there can be a high gradient or difference between tcase and die temps (tjmax), for example TDP of 50W*.35 = 17C (max rated load TD power E8400 = 65W). However this buffer or gradient is highly variable on cooling, ambients, load type (floating point etc), TDP and therefore can not be counted on.
another similar thread here: http://forums.anandtech.com/messageview.aspx?catid=28&threadid=2195801

But that is why tjmax 95C, die temp, is higher than tcasemax (72.4C) casing temps. Intel does not expect me to be running at idle with no heatsink, pulling off IHS's etc, where die temp=IHS temp (within .5C). Normally only way to get temps that high is with load, hence with gradient, hence the tjmax higher than tcasemax.

But there is no sensor or protection at tcase. Only protection is cpu diodes ie tjmax, thus I can run my temp up to 95C on E8400 before throttling occurs on my cpu... at my risk, as I am indeed also at tcase 95C and way over safe temp...because I am running under conditions where tcase=die, as opposed to normal high temp conditions (load) where tj temps higher than tcase.. And I can run temp up to ~115C before cpu shutsdown.

Below is a pic of my E7200, throttling (prochot assertion at bottom in realtemp) has occurred, I am at 104C one core, 108C other core. Delta to tjmax is 7 bit, so can only register up to DTS=0, then goes to 127C and starts backcounting, ie is fubar'd. By the way, I killed my E7200, fried the die from bare die testing. Testing with IHS is pretty safe, with bare die not so much.

See intel specs quote, regarding TCC temp (at tjmax), and next quote is shutdown temp which is 20C hotter than TCC (tjmax)

http://download.intel.com/design/pro...s/31873201.pdf

"An external signal, PROCHOT# (processor hot), is asserted when the processor core temperature has reached its maximum operating temperature. If the Thermal Monitor
is enabled, the TCC will be active when PROCHOT# is asserted....The TCC causes the processor to adjust its operating frequency (via the bus multiplier) and input voltage (via the VID signals). This combination of reduced frequency and VID results in a reduction to the processor power consumption."

http://download.intel.com/design/pro...x/31873401.pdf
"In the event of a catastrophic cooling failure, the processor will automatically shut down when the silicon temperature has exceeded the TCC activation temperature by approximately 20 to 25 °C. At this point the system bus signal THERMTRIP# goes active and power must be removed from the processor."