Processor experiencing unusual heat fluctuations (single core temperature rise)
Processor experiencing unusual heat fluctuations (single core temperature rise)
Hello! I'm looking for some guidance regarding my i7-8700K CPU. It's been a couple of years since I originally purchased it, and the thermal paste was replaced with liquid metal by the owner—reportedly allowing stable 5GHz performance on a custom water loop with excellent temperatures. However, due to circumstances, I haven't been able to find a compatible motherboard until recently.
Once installed, I noticed unusual behavior from the cooler: it would rapidly increase and then drop back down in just a few seconds. While not always consistent, it often mimics full-speed operation followed by a slowdown. Monitoring temperatures via CPUID and HWMonitor showed most readings were normal, with the CPU sensor staying around 35°C and rising to about 50°C under load. Cores 0 through 5 stayed cool, but core 1 and the "package" idle at around 45°C, then spiked to 100°C quickly when any workload was applied. This rapid fluctuation caused the CPU to struggle, constantly trying to adjust speeds instead of maintaining stable performance between 800Hz and 4.7GHz.
I've checked the temperatures again after adjusting the cooler settings in Intel Extreme Tuning, which reduced thermal throttling. Now it's boosting to about 4.4GHz, with only minor temperature spikes reaching around 96°C. The system still runs smoothly across a wide frequency range, though the spikes are less severe.
I'm considering upgrading my case and cooling setup—planning to switch to a better cooler like the SilentiumPC Fortis or an AIO unit. I'm also thinking about a case such as the SilentiumPC Regnum RGB (with full mesh front and glass sides) and will likely install case fans in three pairs each for intake and exhaust. The only adjustments I've made so far are XMP profiles and lowering one core's speed.
I think the liquid metal has become dry and needs to be changed, but there hasn’t been enough testing on it to confirm a regular replacement schedule. I’d also consider installing CPU-Z since it appears more dependable for what you’re checking. If the thermal paste between your CPU and cooler isn’t spreading properly—especially if you’ve replaced it too often—it could be the issue. I agree with Helilan that your CPU might be struggling. Since the model was released in 2017, and you bought it used in 2019, it’s likely something happened during that time. The original owner selling it probably had other reasons. You shouldn’t be facing problems; I have an i7 8700k on an MSI Z370 gaming plus board.
I was thinking about swapping out the liquid metal, but I’m not sure how long it would last. The thermal paste between CPU and cooler seems fine—it was just installed recently and re-applied over the weekend. Removing the cooler confirmed solid contact and fresh paste quality.
Regarding the previous owner selling it, it was an upgrade they were doing themselves. The impression was that this person was an enthusiast with plenty of funds, likely upgrading to a 9th generation system or something similar.
When I looked up similar issues, some suggested the temperature sensor might be faulty because readings fluctuate too much. Anyone have thoughts on that? Also, my CPU-Z shows clocks but not temperatures. EDIT: The CPU was purchased new on November 19, 2018. I didn’t have a warranty due to modifications, but I have proof of purchase. Updated June 21, 2021 by Impatient Traveler
if he moved from 8th to 9th generation then he likely had funds available or was just trying to keep up, but that doesn't mean he was smart about it. Switching from 2nd to 8th generation is an upgrade, yet jumping from last year to this year isn't. It's similar to people changing phones every year or so—just a simple and unnecessary expense. There might be a faulty sensor involved, though I can't confirm. It probably makes sense when temperatures fluctuate wildly by 60 degrees.
Consider using a quality thermal paste instead of liquid metal. Stick to whatever you had for your cooler. Liquid metal won’t really matter unless you’re chasing top performance. If your CPU doesn’t have an IHS seal, the socket will keep it in place. Just note that once you take it off later, the IHS might come loose—only do this if the paste isn’t conductive. (Kryonaut works great) Clean the liquid metal thoroughly; I’m not sure about the 8700k design, but many chips have parts near the die that could burn if shorted. Poor paste or liquid can cause huge temperature changes, making a CPU switch from normal to throttling in seconds. If the paste fails, there might be no contact between the die and IHS.)
I was considering swapping the liquid metal with something more reliable. It wouldn’t ruin anything and would cost roughly the same as a replacement tool I’d probably never need again. However, I’m a bit nervous about giving it to someone unfamiliar, plus I can’t take it apart for a while since it’s my main work device.