small adjustment to 8600k performance
small adjustment to 8600k performance
Hello everyone.
I've optimized my 8600k chip to run at 4.9ghz @ 1.28v on a Z370 ASRock Extreme4. However, during a 2hr 45min prime95 small fft stress test the clock would swing between 4.9ghz and 4.8ghz repeatedly. I kept thermal throttling in mind but max temperatures stayed at 61°C throughout the session, including during 3DMark and Cinebench. The only stable periods were when running AIDA64 and Intel XTU tests, or when I disabled speedstep in BIOS. All stress tests completed without issues, and gaming plus general use performed well over the weekend.
I disabled AVX in the prime95 configuration and lowered AVX settings in the BIOS to 1. The cache ratio remains at 44. I maintain a fixed voltage of 1.28 with LLC set to Level 1. Raising the voltage to 1.3–1.35v didn’t affect the fluctuations.
Perhaps a bit overly cautious (but true), I’m wondering if I might be missing something that other users in the coffee lake community could point out and if they’ve experienced similar issues.
Standard room temperature is around 22°C or 72°F. Your space feels quite chilly, which likely accounts for the low core temperatures you're seeing. Enabling thermal throttling is essential; turning it off might lead to serious issues if your H110i pump malfunctions unexpectedly. SpeedStep won't function properly when Power options are set to High Performance. The spikes you noticed may stem from background processes or services that overlap with your measurements. Have you reviewed Task Manager? Each Core includes a Digital Thermal Sensor (DTS) that operates separately. Intel states the DTS response time is 256 milliseconds, roughly a quarter of a second. With numerous processes running...
I don't think you have anything to worry about. CPUs have a tendency to fluctuate in Prime95 during stress testing. Nice overclock.
urbancamper
...
CPUs often show changes in Prime95 under stress. Good overclocking result.
urbancamper
,
Blend provides a changing workload, whereas Small FFTs deliver consistent performance. Check the charts:
SpeedFan displays 13 minutes of data, illustrating unique thermal patterns for each test.
Left to right: Small FFTs, Blend, Linpack, IntelBurn Test.
Observe the stable thermal pattern of Small FFTs, enabling precise Core temp readings.
Maintaining a consistent 100% load is essential for reliable thermal analysis, ensuring CPU, cooler, socket, motherboard, and voltage regulators reach thermal equilibrium.
mrfungi
,
Your core temps are impressive. Here’s the ideal temperature range:
Temperatures over 85°C should be avoided.
Lower temps under 80°C are better.
Temperatures shift with room temperature.
Q: What is your room temperature?
This is why I'm puzzled. I've performed numerous prime95 FFT tests before and anticipated fluctuations between 4 to 8 MHz, yet not consistently at 100/200 MHz. I'm familiar with variations during different power levels or loads, but during stress testing I haven't observed such consistent changes except during thermal throttling.
I've turned off C-states in an effort to avoid this issue, but it hasn't worked. I also disabled CPU thermal throttling in the BIOS as a precaution against possible sensor anomalies. The only time I managed to prevent the fluctuation was by disabling Intel SpeedStep, which I prefer because it allows downclocking during low load or idle periods. Windows power settings are set to High Performance as well.
As for your room temperature, it ranges from 14 to 18 degrees Celsius.
Standard conditions refer to a room temperature of 22°C or 72°F. Your space feels quite chilly, which likely accounts for the low core readings. Thermal throttling on the CPU must remain active; turning it off might lead to serious issues if your H110i pump malfunctions unexpectedly. SpeedStep functionality won’t operate properly when Power settings are set to High Performance. The fluctuations you’re noticing could stem from background processes or services that align with your observations. Have you reviewed Task Manager? Each Core includes its own Digital Thermal Sensor (DTS), operating separately. Intel’s guidelines suggest a response time of 256 milliseconds, roughly a quarter of a second. Given the numerous background processes and services running, it’s typical to experience quick and irregular core temperature changes, especially shortly after power-on, which usually stabilizes over time. Any software activity will display CPU utilization in Task Manager; unnecessary tray items, startup entries, or processes that contribute to excessive spikes can be turned off. The 6th Generation processors brought "Speed Shift" technology in Windows 10, offering quicker adaptation to workload changes compared to "SpeedStep" because of a greater number of speed and voltage transition points. Since the 7th and 8th Generation Speed Shift is twice as rapid as the 6th, some users report core temperature spikes leading to fan RPM variations at idle. Manufacturers are working on BIOS updates that provide distinct SpeedStep and Speed Shift configurations with more adaptable fan curves and delay settings. Spiking cannot be fully removed—it can only be reduced. Despeaking is most effective. Enhanced cooling, lowering clock speeds, and minimizing Vcore and LLC values also help curb spikes. But given your low core temperatures, unless the fluctuations are affecting gameplay performance, you shouldn’t worry about sleep disruption. You may find useful information here: Intel Temperature Guide -
CPU thermal throttling is reactivated, but don't worry. I turned it off just to test whether it could be a cause of these core changes. Regardless of clock or voltage settings, these frequency shifts still happen.
I don’t care about temperature spikes as long as they stay below 85-90°C and the variation range isn’t too extreme to worry me. Still, these quick temperature swings seem to help explain the core frequency changes (which previously didn’t bother previous intel chips when overclocked properly). That makes sense with what you’ve shared and how I’m dealing with this situation.
I keep my startup process at its simplest. I haven’t seen anything unusual in Task Manager either. I’ll experiment more with BIOS adjustments to see if any improvements come through. I’m starting now, maybe it’s worth trying to regain some composure before finishing.
Thanks for the feedback and the guidance—it really helps!