Real Temp - New temp program for Intel Core processors

[rge]

about 8 hours of drilling holes in cpus and comparing die temps to tcase temps....curiosity was getting to me.

I borrowed an accurate surface temp thermocouple, has flat tip as opposed to wire one, and was reading almost exactly in line with IR gun, sometime .5C higher, sometimes 1C lower, mainly from different sensor sampling times.

First on pentium 4 since it has a soldered IHS. I measured with both IR gun and fluke temp probe which reads surface temps...and slowly brought up to shutdown temp....It shutdown at an average of ~76C Tcase (would ?throttle for few seconds and reduce temp 2-3C then cut off) I did this about 15x and mapped out a circle on the center of cpu that gave same temps consistently and same cutoff Tcase temps consistently (within +-1C). I then drilled a hole in the center, through half of the marked area, leaving other half for tcase measurement. When I got down to solder I switched from drill to dremel....saw small hole of mirror surface in couple spots...but a little aggressive with dremel and scratched core surface...but cpu worked fine.

Ran the temp up and could hold it under cutoff for minute or so with big fan (equilibration in seconds anyways) and running probe from die to tcase back and forth, probably tested 20 or more runs and hundred times...always 3-5C gradient, vast majority reads ~4C higher die temp than tcase.

Then ran it slowly up to cutoff temp 7X reading Tcase each time beside the hole, and then 7x more reading die temp with surface probe in the hole.

Die temp reaches avg. 80.7C, then throttles, drops temp few C for few seconds, then cuts off.

Tcase temp reaches ~76.3C then throttle, drops temp few C for few seconds, then cuts off, highest temp reached recorded.

Cpu shutdown die temps, highest recorded, measured with fluke temp probe
80.8, 80.1, 81.2, 80.5, 80.4, 80.9, 81.3

Shutdown Tcase temps (before and after drilling holes ~ same) measured with fluke temp probe.
76.5, 76.1, 76.7, 75.7, 75.6, 76.6, 77.1

Also using IR to measure Tcase and fluke probe to measure Tcase, tracks within half a degree celsius...but then using IR to measure Tcase and surface probe to measure die, die temp always 3-5C and avg 4C higher.

A couple of interesting things, as soon as power cuts off, Tcase =Tdie, ie as soon as die temp is no longer producing heat, equilibration is instantaneous.

Also, I stacked another IHS on top of IHS, and again only get 2C gradient...I think that is b/c die to IHS is closer to core heater than IHS to second IHS, and also going from small surface area to larger surface area incurs bigger gradient vs identical surface areas of IHS to IHS.

But I am now convinced on cpus with a solder attach, there is going to be a ~4C gradient from die to Tcase when heatsink is off. Hence need to add 4C to IR Tcase temps to get tjmax. So I am back to thinking E8400 tjmax is about right at 100C.

May post more this weekend if do some more playing.

I have not drilled my E8400 yet, that will be last test. After benching and failing to get 5hz 3x now, only 4.9ghz, even tried 1.9v yesterday...my E8400 now has degraded for 3rd time and needs 1.45v for 4 ghz (passes 10 linpack)...I would like to do same test on E8400 since it runs at slightly lower volts....but would be surprised if saw anything different than 3-4C at this point. But not going to drill it until I decide on getting E8600, q9650 or nehalem and wont decide that til nda is up and people post more nehalem results...as my E8400 is the only cpu in my house without a hole in it (other than wifes)