Large changes in VCore and temperature observed at 8700k
Large changes in VCore and temperature observed at 8700k
If you execute the small FFT with any update of Prime95 after v26.6, you’ll almost certainly experience extremely high temperatures. This is because a small FFT operates at a full load with no interruptions. Other stress test tools such as cinebench, Aida 64, occt, and Intel burn test typically apply a variable load percentage since they account for RAM usage. Small FFT only consumes the CPU and minimal memory. Since Prime95 introduced AVX (and similar instructions) in version 26.6, these tests become very demanding on the processor and generate significant heat. The surprising aspect is that games rarely use AVX at all; therefore, any temperature readings from such tests reflect only a subset of users working with specific rendering or encoding software. In gaming context, performing a small FFT on the latest Prime95 version feels like pushing the CPU to over 120% utilization—completely ineffective.
I've overclocked my 8700K to 4.9Ghz at 1.27v now. I downloaded P95 26.1 and ran small fft for 4 hours straight. The AIO isn't hot at all niether are the tubes or the radiator, its frickin weird. Here's a screenshot before I stopped it
Here's a screenshot
https://imgur.com/a/52AzI
I'm having trouble seeing the print too small. With that voltage and 8 workers, the 280mm aio should be around 70mm max, using a kraken x61 on a 3770k @4.9 1.32v, I was getting 72-76°C depending on the mode setting. Your temperatures shouldn't be much higher. If they are, it's probably not an OCP issue but more likely a setting or mount problem with the aio. Could you explain how the pump is installed, the speeds, fan settings, mount, and USB connections?
Karadjgne :
Ugh, I can't see the print too small. At that voltage and with 8 workers that 280mm aio should be somewhere in the 70's at most, with a kraken x61 on a 3770k @4.9 1.32v I was getting 72-76°C depending on the mode setting. Your temps shouldn't be much different.
If your temps are higher than that, I'm doubting it's a OC issue, more likely a setting or mount issue with the aio itself.
Could you give a run-down on exactly how the pump is installed, speeds, fan speeds, fan mount, USB etc?
Hi,
Here's a closer view of it
https://imgur.com/a/AVxHu
The rad is mounted at the front of the case, 100% speed set in BIOS and I've remounted the AIO with fresh thermal paste twice.
the core temp reading is around 1.40v, which seems like another setting in your bios is affecting your 1.225v. the temps with your cooler also suggest a high vcore. the hd3 bios setup isn’t clear to me, but I’d look into it more and check if anything is altering your vcore. for reference, i reached 80c max at 1.38v bios, 1.392v with coretemp/cpu/hwmonitor for 5.0ghz, and i’m also using liquid metal delid.
UsmanGTA:
Hi everyone,
I recently acquired my 8700k and decided to push it overclock after playing with it for a while. Here are my system details:
- CPU: 8700k
- Motherboard: GB Z370 HD3
- Storage: 240GB NVMe SSD
- Graphics: GB GTX 1080 Windforce
- Power Supply: Super Flower Silver 650W
- Cooler: Cooler Master MasterLiquid Pro 280
- Additional Cooler: Cooler Master MasterGel Pro
I’m running this setup and have already adjusted the overclock settings. My current configuration is:
- Clock speed: 100 x 48 = 4.8GHz
- VCore in BIOS: 1.225v
- LLC: Turbo
I ran Cinebench twice back-to-back, using AIDA64 and Realbench for a while. Everything performed well with temperatures staying between 50-75°C. But the fluctuations were quite noticeable—temperatures spiked from 35°C to 75°C in seconds and then dropped rapidly after testing ended.
Prime95 1344k was stable for about an hour, keeping temps around 55-65°C. However, Core Temp reported a VID of 1.38-1.44v even though I set it to 1.225v in BIOS.
Small FTTs also ran for an hour with temperatures between 80-90°C, occasionally jumping to 93°C on some cores.
I haven’t seen any BSOD errors yet. If anyone could clarify a few terms or explain what’s happening, that would be really helpful.
Thanks in advance.
It’s normal for these temps to spike immediately when testing starts—your processor is being pushed hard. I’d check the video here:
https://www.youtube.com/watch?v=CoUtA7DKXhU
It covers some of the settings and voltage details that might help fill in gaps.
Also, consider setting AVX to 3 and LLC to 6 for better performance.
I wouldn't be surprised that your CPU doesn't start overheating, as a voltage above 1.40 on a non-delid setup suggests thermal throttling. I managed 5GHz at 1.365 stable for 12 hours using Avx3 llc 6 on no delid with 82°C max temps. When desoldered, my temperatures stayed at 70°C during p95.