6700k Stress Test Temperature Too High

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H

HatrixMouseh

Commendable
Oct 25, 2016
5
0
1,510
I7-6700k
ASUS Sabertooth Z170 S
Corsair Ballistix LT
Samsung 850 M.2
Kraken X61
EVGA 970GTX

I threw everything together with caution, testing all main hardware pieces with power/POST each new piece I added (the Sabertooth has an awesome LED POST notification on the board!)

Replaced the thermal paste between the Kraken and I7 with Arctic Silver 5.
Start computer, load OS, everything running fine.

Temperatures idling around 25-30C, which seems great! (Intel states the 6700k idles about 30-40C, pending ambient temperature)
Load up Prime 95, and start the Stress Test (for max heat/CPU only), and the temperatures shoot up to 80, and steadily increase to about 85-87 within 10 minutes.

- I've already run Intel's Processor Diagnostic Tool, and that passes (not sure if that says anything).
- Double-checked paste between cooler and CPU
- Could physically hear water flowing in the X61, and fans are working.
- CAM recognizes X61 fans and temperatures. Coolant temperature stays fairly low during benchmark. (< 40C, don't really see increase.)
- Running Phantom 530 Case with enough fans (NZXT Airflow Series - 200mm front, (2) 140mm top pulling through X40), and 140 pushing out). Waiting on (2) 140mm for bottom intake.
- Cable management excellent

So, I'm at a loss right now. I'll have to dive into it again once I get home, but I really don't think 85C should be possible with the liquid cooling in effect.
 
Solution
Ecky
Two things:

1) Prime95 is not recommended for stability testing anymore, at least not versions past 26.6, because it uses AVX2 instructions. When AVX2 instructions are used, the CPU increases its voltage by 100mv, which causes excessive temperatures. Typical desktop workloads do not use AVX2 instructions, so Prime95 after 26.6 is not representative of typical desktop worloads.

2) 85-87c will not hurt your CPU, though it's a bit warmer than is ideal. Throttle temperature (what Intel programmed the CPU to stay under for long-term reliability) is 100c. Thermal shutdown is at 130c.

What are your temperatures under real-world workloads?
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Ecky

Ecky

Illustrious
Feb 3, 2013
7,592
2
38,960
Two things:

1) Prime95 is not recommended for stability testing anymore, at least not versions past 26.6, because it uses AVX2 instructions. When AVX2 instructions are used, the CPU increases its voltage by 100mv, which causes excessive temperatures. Typical desktop workloads do not use AVX2 instructions, so Prime95 after 26.6 is not representative of typical desktop worloads.

2) 85-87c will not hurt your CPU, though it's a bit warmer than is ideal. Throttle temperature (what Intel programmed the CPU to stay under for long-term reliability) is 100c. Thermal shutdown is at 130c.

What are your temperatures under real-world workloads?
 
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Solution
H

HatrixMouseh

Commendable
Oct 25, 2016
5
0
1,510

I haven't done any real-world workload testing yet, as I was just trying to stress test first to see how things ran. I'll have to throw something up and post the results.

I've also just read about the newer versions of Prime95/AIDA64 being a bit overkill for the current gen iCore processors. So I'll download 26.6 when I get home and try that again. I read anywhere from 10-20C cooler, but the CPU load is also off for the earlier version, but the Task Manager will verify the 100% core load.
 
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CompuTronix

CompuTronix

Intel Master
Moderator
Nov 13, 2006
6,374
279
38,240
HatrixMouseh,

Sorry, but your statement that I put in bold is not accurate.

Task Manager may not always correctly report CPU Utilization. Keep in mind that "CPU Utilization" does not always equal "CPU Workload".

Depending on BIOS versions and applied Vcore, when most motherboards are configured to run Intel processors at Default / Stock settings, Core Temp and other utilities that measure Power (Watts) will show that Prime95 V26.6 Small FFT's will load i7 and i3 processors typically within 3% of their Thermal Design Power (TDP).

TDP is precisely why I recommend P95 V26.6 in my Intel Temperature Guide. And since Small FFT's is a steady-state 100% workload that produces steady Core temperatures, it's the perfect test for thermal testing (not stability testing) because it so closely replicates Intel's TDP lab tests to give you a valid thermal baseline.

There are no other utilities which offer a steady-state workload so close to stock TDP.

The "Charts" in SpeedFan span 13 minutes, and show how each test creates different thermal signatures.

Shown above from left to right: Small FFT's, Blend, Linpack and Intel Burn Test.

Note the steady-state thermal signatures of Small FFT's, which allows accurate measurements of Core temperatures. A steady-state 100% workload is critical for thermal testing.

Steady-state workload thermal test utilities (in order of typical % Workload):

Heavy Load - Stress CPU: 107%
Prime95 V26.6 - Small FFT's: 103%
FurMark - CPU Burner: 96%
Intel Processor Diagnostic Tool - CPU Stress Test: 90%
AIDA64 - System Stability Test - Stress CPU: 64%

Fluctuating workload stability test utilities (in order of typical % Workload @ peak):

IntelBurn Test - High: 120% (IBT is NOT an official Intel utility)
OCCT - CPU Linpack: 109%
Asus RealBench - Stress Test: 103%
Intel Extreme Tuning Utility - CPU Stress Test: 94%

For thermal testing I recommend Prime95 Version 26.6 Small FFT's .

For stability testing I recommend Asus RealBench.

Also, you might want to give this Sticky a read: Intel Temperature Guide - http://www.tomshardware.com/forum/id-1800828/intel-temperature-guide.html

CT :sol:
 
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