The CPU temperature increased abruptly from 75 °C to 100 °C
The CPU temperature increased abruptly from 75 °C to 100 °C
davidchunco
,
On behalf of Tom's Moderator Team, welcome aboard!
If you ran the latest version of Prime95, then you can expect unrealistically high Core temperatures. Also, if you ran "Blend" rather than "Small FFT's" you can expect your Core temperatures to fluctuate. Here's why:
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...
Davidchunco, On behalf of Tom's Moderator Team, welcome here! If you were using the newest version of Prime95, you might encounter unusually high Core temperatures. Additionally, choosing "Blend" instead of "Small FFT's" can lead to unstable Core readings. Here’s the explanation: Intel evaluates their processors in tightly regulated settings at full TDP. Prime95 version 26.6 Small FFT's is perfect for CPU thermal assessments, as it delivers a consistent 100% workload with Core temperatures that usually stay within a few percentage points of TDP. It closely mimics Intel’s official testing environment. This tool is also the one Real Temp uses to verify Core temperature sensors. Avoid using Prime95 versions older than 26.6 on 2nd through 8th Generation i3, i5, or i7 CPUs—these models include AVX Instruction Sets. Versions after 26.6 execute AVX code on the CPU’s Floating Point Unit (FPU), which can push Core temperatures up by as much as 20°C. AIDA64’s FPU test confirms similar outcomes. You can disable AVX in Prime95 versions beyond 26.6 by adding "CpuSupportsAVX=0" to the local.txt file in the Prime95 directory. However, since the results match those of version 26.6, it’s simpler to stick with that version. AVX doesn’t impact Core i1st Generation, Core 2, Pentium, or Celeron chips because they lack AVX support. Download and run only Small FFT's for a short period—10 minutes max. • Prime95 v26.6 – http://www.mersenneforum.org/showthread.php?t=15504 If you’re overclocked and use AVX-intensive applications like rendering or transcoding, consider lowering Vcore and Core speed, or upgrading your cooling solution and fan setup to keep temperatures below 85°C. Many 6th, 7th, and 8th Generation boards handle AVX by offering BIOS offset adjustments, but a 4th Generation board doesn’t support this feature. Asus RealBench performs realistic AVX workloads within ± a few % of TDP, making it ideal for overall system stability checks—overclocked or not. • Prime95’s default test, Blend, provides a variable workload for memory testing, while Large FFT's combines CPU and memory evaluations. Both fluctuate, which isn’t ideal for thermal analysis. Other stability benchmarks like Linpack and Intel Burn Test have peak loads at 120% of TDP, making them unsuitable for thermal evaluation. OCCT, which runs Linpack and Prime95, stops the CPU tests once temperatures reach 85°C. The charts in SpeedFan display thermal behavior over 13 minutes, illustrating how each test generates distinct heat patterns. Displayed from left to right: Small FFT's, Blend, Linpack, and Intel Burn Test. Observe the consistent thermal profile of Small FFT's, which ensures precise Core temperature readings. A stable 100% workload is essential for accurate thermal assessments. Also shown: Small FFT's, Intel Extreme Tuning Utility CPU Test, and AIDA64 CPU Test. Intel Extreme Tuning Utility also provides a variable workload. While AIDA64’s test maintains a steady load, it operates below TDP levels—insufficient for reliable thermal checks. All other AIDA64 combinations are fluctuating, which is not ideal for CPU heat monitoring. Also, AIDA64 is not free software, so the trial version expires after use. Here’s the recommended core temperature range: Temperatures exceeding 85°C should be avoided. Core temperatures change with ambient conditions. Peak readings happen during stress tests like rendering or transcoding, but drop during lighter tasks such as apps and gaming. Workloads vary significantly between games; idle temps under 25°C usually reflect cooler rooms below 22°C. If you want to understand how to accurately measure Core temperatures and set a reliable baseline, refer to this guide: Intel Temperature Guide - Once more, welcome aboard!