i7 7700K OC, 4.8 GHz @ 1.350 Volts PROBLEM
i7 7700K OC, 4.8 GHz @ 1.350 Volts PROBLEM
It’s very probable your bad experience with Prime95 stemmed from the "AVX" problem, which confuses many users who aren’t prepared. This situation isn’t uncommon since most people don’t realize what’s happening. They often overlook important details like the specific version, test used, and especially the AVX aspect. The quick response is to avoid using AVX, but it doesn’t explain why. Here’s a clear and full explanation...
I have experienced this myself. I reviewed some independent articles, watched certain YouTube videos, and read an overclocking guide for my motherboard (Gigabyte Z270X Gaming K5) produced by Gigabyte. I adjusted all the settings, but Prime95 still displays the error. I tested it with a few other CPU burning tools, and each one worked properly. Currently, I have reduced the overclock to 4.5GHz @1.265 Volts, yet one of the workers (Worker #8) continues to encounter errors in Prime95.
Which iteration of Prime95 is being considered? (It significantly impacts the results).
What type of stress test should be used?
At which room temperature is this being evaluated?
CT
I'm working with prime95 v29.8, version 3, executing the "Blend" test across all 8 threads. The room temperature is around 23°C. After several attempts, I've moved on from Prime95 to more reliable programs like Aida64 and FurMark CPU Burner, achieving the best results at 4.6GHz with 1.265V. Beyond that speed, the CPU reaches 90 degrees. I'm using a Fractal Design Kelvin T12 AiO.
It’s very probable that your negative experience with Prime95 stemmed from the "AVX" problem, which confuses many users who aren’t fully informed. Although numerous forum participants recognize the AVX issue, most still assume everyone else is equally aware. As a result, they don’t specify the exact version, test used, or importantly, the details about AVX. The concise response is to avoid using AVX, but this doesn’t explain the reason. Here’s a clear and thorough explanation... "Stress" tests are divided into two types: stability tests with changing workloads, and thermal tests with constant workloads. Prime95 version 29.8 Small FFTs (with all AVX disabled) works best for evaluating thermal performance because it matches Intel’s specifications as a consistent 100% load with stable core temperatures. No other tool can replicate Intel’s thermal workload as closely. Tools that don’t stress or under-stress the processor will offer a reliable baseline. Here’s a comparison of tools categorized by thermal and stability tests, based on TDP percentages, averaged across six processor generations at standard settings, rounded to the nearest five percent: Although these tests cover from 70% to 130% TDP, Windows Task Manager treats every test as 100% CPU usage, which reflects processor activity rather than actual workload. Core temperatures directly reflect power use (in watts), which is influenced by the workload. Prime95 version 29.8 Small FFTs (with AVX disabled) delivers a consistent 100% load, even when TDP exceeds normal limits due to overclocking. If core temps stay below 85°C, your CPU should handle demanding real-world tasks without overheating. • AVX – Advanced Vector Extension instruction sets were added with the second-gen Core processors, followed by AVX2 in the fourth generation and AVX512 in later high-end desktops (such as certain X-Series, Extreme, i9, and i7 models). Using Prime95 with AVX enabled creates an overly demanding 130% workload, which can harm stability and push your CPU beyond safe limits. Second and third generations are somewhat less impacted, but temperatures on fourth through ninth generations may rise by over 20°C. Many motherboards in the 6th to 9th generations include AVX fixes via BIOS "offset" adjustments (downclocking). If core temps exceed 85°C, you may need to set a BIOS profile for AVX and non-AVX software. Except for a few specialized tools and apps, real-world applications (like rendering/transcoding) with AVX and recent games should not surpass Prime95’s workload without AVX support. According to Intel’s datasheets, TDP and thermal specs are confirmed "without AVX." In versions from 27.7 to 29.4, you can disable AVX by adding CpuSupportsAVX=0 in the local.txt file found in Prime95’s directory. Since core temps remain unchanged without AVX, it’s simpler to stick with version 29.8. You can also choose 26.6, which lacks AVX. The results below illustrate Small FFTs and Blend (without AVX), along with Linpack and IntelBurn Test on a 7700K. Observe the consistent thermal behavior of Small FFTs, which ensures accurate core temperature readings. Maintaining a steady 100% workload is essential for reliable thermal testing, so the CPU, cooler, socket, motherboard, and voltage regulators must all work together to keep temperatures at 85°C or below. Consider reviewing Section 11 – Thermal Test Basics: Intel Temperature Guide https://forums. Still unsure? Try Prime95 again using Small FFTs with all AVX disabled. I’m confident the outcomes will be much more comfortable.
It now functions properly! The sole factor preventing it from reaching 4.8 remains my Fractal Kelvin T12. Even at 4.6, I'm achieving high 80s results!