core temp difference

[zxcv2qwer]

Hey guys. I'm just wondering why my other cores is much hotter than the rest. I also tried another processor and I noticed the core temp differences are closer than the other one.

http://imgur.com/a/rpf8s

 

[CompuTronix]

zxcv2qwer,

On behalf of Tom's Moderator Team, welcome aboard!

Intel's specification for Digital Thermal Sensor (DTS) accuracy is +/- 5°C. Although sensors are factory calibrated, deviations between the highest and lowest Cores can be up to 10°C. Deviations on processors using Turbo Boost might exceed 10°C by a few degrees.

• Your screenshot shows both processors at 100% load.

• The i5 4690K is well within spec with a deviation between highest (73°C) and lowest (69°C) Cores of 4°C.

• The i7 4790K is well outside spec with a deviation between highest (100°C Throttle temperature) and lowest (74°C) Cores of 26°C.

The i7 4790K clearly shows defective Thermal Interface Material (TIM) between the Die and the Integrated Heat Spreader (IHS). This is grounds for RMA. Since the i7 4790K launch date was 2nd Quarter of 2014 - http://ark.intel.com/products/80807/Intel-Core-i7-4790K-Processor-8M-Cache-up-to-4_40-GHz - it's possible that your processor may still be covered under Intel's 3 year warranty.

3rd through 7th Generation mainstream processors use a non-standard Thermal Interface Material (TIM) between the Die and the IHS, which increases the temperature gradient. "Indium" solder, which has superior thermal conductivity, was instead used in 2nd Generation and earlier processors, and is used in many "Core X" (formerly called High End) Desktop Processors - http://ark.intel.com/products/series/123588/Intel-Core-X-series-Processors#@desktop

Since the bonding material which seals the perimeter of the IHS to the Substrate is slightly too thick, this tends to increase the space between the Die and the IHS, which can cause the TIM to compress unevenly. The effect is that many processors show wide deviations between Core temperatures, or one Core which runs much hotter than it's neighbors.

This has encouraged some overclockers to "de-lid" or remove their processor's IHS and replace Intel's TIM with liquid metal TIM, allowing thermal conductivity much closer to Indium solder, which decreases the Die to IHS thermal gradient. Typical results are significantly lower Core temperatures and less deviation between Cores. You can safely de-lid by using the Rockit 88 De-lidding Tool - https://rockitcool.myshopify.com/

Silicon Lottery - https://siliconlottery.com/collections/all/products/delid - is a company that tests, bins and sells "K" CPU's. They also offer de-lidding services, and give the following figures on how much Core temperatures at 100% workload are improved by de-lidding:

7th Generation ... Kaby Lake - 12° to 25°C
6th Generation ... Skylake - 8°C to 18°C
5th Generation ... Broadwell - 8°C to 18°C
4th Generation ... Devil's Canyon - 7°C to 15°C
4th Generation ... Haswell - 10°C to 25°C
3rd Generation ... Ivy Bridge - 10°C to 25°C

Beware that de-lidding will void your warranty.

Note: Intel uses engineering samples with soldered Integrated Heat Spreaders for testing and developing specifications.

If you want to learn more about temperature, then read this Sticky: Intel Temperature Guide - http://www.tomshardware.com/forum/id-1800828/intel-temperature-guide.html

Once again, welcome aboard!

CT