Different stress test results on Aida64 and prime95

ahuang1031

Prominent
Aug 21, 2017
4
0
510
Hello,

I finally decided to OC my 7700k but got mixed results with prime95 and aida 64.

Currently I am OC'd at 4.8ghz at 1.3 volts. Aida64 runs did not dispaly a temp higher than low 70s after a 30 minute run. Prime95 showed steady temperatures until after 10 minutes and immediately spiked from mid 70s to low 90s. I stopped the test when that happened. The temps seem to be the only thing yielding mixed results with this OC profile, the stability of it seemed fine as all cores and threads were utilized at 100%

However, when I tried OCing to 4.9 ghz at 1.3-1.375 volts I got the same issue with temps as the first OC profile and also mixed stability results.

On Aida 64 everything seemed stable and in check. On prime95 all cores seem to be at 100% until about the 3 minute mark and then 1 core/two threads wont be utilized at 100% anymore.

I am new to overclocking and was wondering if anyone can offer insights on my experience. I did try using real bench but only had about 15 minutes on each test. Temps were stable between low 70s and low 80s. No crashing.

Would it be considered stable if the tests passes on aida64 and not prime95? All feedback is appreciated.
 
Solution
Guys,

The issue with Prime95 is strictly version dependent, which is a well known problem. For the record, there is nothing wrong with version 26.6.

Also, 100% CPU utilization seldom equals 100% workload which means 100% TDP.

Intel tests their processors under carefully controlled conditions at 100% TDP. Prime95 version 26.6 Small FFT's is ideal for CPU thermal testing, because it's a steady 100% workload with steady Core temperatures that typically runs Core i variants with Hyperthreading and Core 2 processors within +/- a few % of TDP. No other utility so closely replicates Intel's proprietary test conditions. This is also the utility that Real Temp uses to test Core temperature...
I have been told that Prime95 does not play well with the Intel Core i7's and can cause problems to the CPU. People on Tom's forums pointed me to use RealBench, Aida and IntelBurn instead as they will give your CPU a good test in real world temp conditions..There are plenty of threads on Prime95 and intel where P95 puts way to much load onto a i7..Hopefully others can chime in...
 

CompuTronix

Intel Master
Moderator
Guys,

The issue with Prime95 is strictly version dependent, which is a well known problem. For the record, there is nothing wrong with version 26.6.

Also, 100% CPU utilization seldom equals 100% workload which means 100% TDP.

Intel tests their processors under carefully controlled conditions at 100% TDP. Prime95 version 26.6 Small FFT's is ideal for CPU thermal testing, because it's a steady 100% workload with steady Core temperatures that typically runs Core i variants with Hyperthreading and Core 2 processors within +/- a few % of TDP. No other utility so closely replicates Intel's proprietary test conditions. This is also the utility that Real Temp uses to test Core temperature sensors.

Do not use Prime95 versions later than 26.6 on 2nd through 8th Generation i3, i5 or i7 CPU's, which all have AVX (Advanced Vector Extension) Instruction Sets. Prime95 versions later than 26.6 run AVX code on the CPU's Floating Point Unit (FPU) which causes unrealistic temperatures up to 20°C higher. The FPU test in the utility AIDA64 shows similar results.

AVX can be disabled in Prime95 versions later than 26.6 by inserting "CpuSupportsAVX=0" into the "local.txt" file in Prime95's folder. However, since Core temperatures will be the same as 26.6, it's easier to just use 26.6. AVX doesn't affect Core i 1st Generation, Core 2, Pentium or Celeron processors since they don't have AVX Instruction Sets.

Please download, then run only Small FFT's for just 10 minutes.

• Prime95 v26.6 - http://www.mersenneforum.org/showthread.php?t=15504

If you’re overclocked and run AVX apps such as for rendering or transcoding, you may need to reduce Vcore and Core speed or upgrade your cooler and case fans so Core temperatures don’t reach 85°C. Many 6th, 7th and 8th Generation motherboards address the AVX problem by providing offset adjustments in BIOS. An offset of -2 or -3 (200 or 300 MHz) is usually sufficient. Asus RealBench runs a realistic AVX workload typically within +/- a few % of TDP, and is an excellent utility for testing overall system stability, whether you're overclocked or not.

• Asus RealBench - http://rog.asus.com/rog-pro/realbench-v2-leaderboard/

Prime95's default test, Blend, is a fluctuating workload for testing memory stability, and Large FFT's combines CPU and memory tests. As such, Blend and Large FFT's both have fluctuating workloads which aren’t well suited for CPU thermal testing.

Other stability tests such as Linpack and Intel Burn Test have cycles that peak at 120% workload, which again aren’t well suited for CPU thermal testing. The test utility OCCT runs elements of Linpack and Prime95, which will terminate the CPU tests at 85°C.

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 thermal signature of Small FFT's, which allows accurate measurements of Core temperatures. A steady 100% workload is crucial for thermal testing.

Shown above from left to right: Small FFT's, Intel Extreme Tuning Utility CPU Test, and AIDA64 CPU Test.

Intel Extreme Tuning Utility is also a fluctuating workload. Although AIDA64's CPU test is a steady workload, it's far below TDP, which is insufficient for thermal testing. All other AIDA64 CPU test combinations are fluctuating workloads, which again aren't well suited for thermal testing. Also, AIDA64 is not Freeware, so the Trial version expires.

Here's the operating range for Core temperature:

Core temperatures above 85°C aren't recommended.

Core temperatures increase and decrease with Ambient temperature.

Highest Core temperatures occur during stress tests, rendering or transcoding, but are lower during less processor intensive workloads such as applications and gaming. CPU workloads and Core temperatures can vary greatly between games. Idle temperatures below 25°C are generally due to Ambient temperatures below 22°C.

If you'd like to get up to speed on this topic, learn how to properly test your Core temperatures and establish a valid thermal baseline, then please read this Sticky: Intel Temperature Guide - http://www.tomshardware.com/forum/id-1800828/intel-temperature-guide.html

CT :sol:
 
Solution