Question Underclocked my 8700k to 3.7GHz lower my temps from 99°C --- Is 40°C lowest it can do?

May 28, 2021
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Cooler: H115i RGB pro XT
Ram: 32GB 3200Mhz CL16
Motherboard: ASUS Maximus Hero X Wifi
GPU:6800 XT
CPU is not delidded.

I wanted to test this after my CPU started to spike to 99°C at 5.0GHz 1.37v. When the system was stable I was getting around 78°C under load in game. Recently it started to peak at 99°C and trigger all the fans for 10 seconds every two minutes when in game. Temps are never below 85°C in game. CPU load is 80% in game. I tested 4.7Ghz at 1.35v and temps were still at around 90°C.

I downcloked the CPU to 3.7GHz at 1.15v in hopes to finally see temps below 40°C. You can see the results below 40°C under full load and idle;
View: https://imgur.com/a/z7L3Wui


Cooler pump is working, I can feel and hear it when it kicks in. It was replaced by Corsair 3 months ago and I was getting below 80°C under load for 2 months at 5Ghz. CPU fans are directly connected to Motherboard; not the cooler. I run them at 100% for this test to make sure I am getting best cooling. You can see the Cooler pump is at max speed. I tried resitting the cooler with different pastes. Room temp is 25°C.

Are these numbers reflective of what I should see at 3.7Ghz base speed? What could be the rise of sudden 99°C spikes at 5.0GHz ?
 
those are pretty bad temps for 3.7GHz.

using a 360mm AIO my 8700K @ 5GHz 1.225v never passed 70°C even while heavy stress testing.
idle ~32°, intensive gaming ~62°.

my older 280mm AIO with lower quality fans had similar results with same CPU settings;
~35° idle, ~65° gaming, ~75° while heavy stressing.

what temperatures are your GPU, drives, and memory hitting?
 

Karadjgne

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I7 3770k at 4.9GHz 1.325v
Prime95 small fft 72°C after 1/2 hr stress, no AVX.
Gaming 55°C
Idle 32°C
Ambient temp 23°C
Nzxt Kraken X61 (280mm) Silent mode. (slower curve, fans didn't breach 900rpm).
Control via CAM software.

You shouldn't ever see 99°C with that cpu/cooler combo at 5GHz unless it's running AVX of some sort in a stress test.

Shouldn't even make it to 70°'s at 3.7GHz. Sounds like all you did was back off on the multiplier, but that's not going to change the associated voltages, ring voltage, LLC, current turbo limits etc.

If you want to back out of the OC, you'd realistically need to reset the bios back to factory defaults, then disable turbo/enhanced turbo. Voltages would then be on Auto, so vid/vcore/ring would be much lower, LLC would be standard etc.

But a H115i is plenty large enough that even at 5GHz, you are barely over 1/2 way into the coolers capacity. P95 tests should be closer to the mid-low 70's at best with a non-AVX, small fft load.
 
May 28, 2021
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best with a non-AVX, small fft load.
Is this how I do the test? By selecting custom and then disable AVX;
View: https://imgur.com/a/t9xuT3F


If so this is the result:
View: https://imgur.com/a/SeoJ8Si


Also, I tested selecting the "small FFTs" option. I stoped this test when I see the results at 99C:
View: https://imgur.com/a/BzBl53u


Tests are done at 5GHz at 1.32v. Idles at 38°C . I replaced the thermal paste before starting the tests today. I don't know what I am doing wrong. Thanks for the help.
 
Pumps often become internally fouled with gunk/hard water deposits after a18-36 months, massively degrading cooling performance, so 'feeling your pump buzzing/working, etc.' is not really the same as it actually working correctly, and is highly possible your likely reason for current high temps....
 
May 28, 2021
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Pumps often become internally fouled with gunk/hard water deposits after a18-36 months, massively degrading cooling performance, so 'feeling your pump buzzing/working, etc.' is not really the same as it actually working correctly, and is highly possible your likely reason for current high temps....
My current cooler was replaced 2 months ago by Corsair. It looked like brand new to me. I don't know how I can make sure it's working. Temps still reach over 95C depending on the case, sometimes in game (Warzone). Stress test softwares can load the CPU 100% but not all can cause temps above 90. Only specific software can push temps between 90 and 99C.
 
May 28, 2021
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You should be able to do the small fft, then select the AVX2, then AVX as disabled when checked. Shouldn't have to do custom.

How is the pump controlled? Through iCue software? Or bios?
Pump is controlled by iCue. Cpu fans controled by motherboard. Doesn't matter what speed they run at. I even run them at 100% on purpose to cool it down. Doesn't help at all.
 
May 28, 2021
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How/where is the pump/radiator mounted?

That's odd. The pump should always be running and you should need to stick your face right upto it to hear it at all. Really sounds like there is a good sized airbubble trapped in the pump, and the temps support such.
Radiator is mounted on top. Pump is well below the radiator.

Pump is always running. I can hear and feel it when speed it up manually in the iCue software . Pump runs at 2000s rpm at base, I select the fastest option which pumps it up to 2700s.
 
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How/where is the pump/radiator mounted?

That's odd. The pump should always be running and you should need to stick your face right upto it to hear it at all. Really sounds like there is a good sized airbubble trapped in the pump, and the temps support such.
I get real close to hear the pump. Also, I can't feel any temperature difference in the pipes when I touch them when CPU is under load. I imagine one pipe should be hot, while the other is cool. Isn't it how it's supposed to work?
 

Karadjgne

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No. When running right there's generally only a 2°C - 3°C difference between in the input and output. It's like a pan of water on a stove, even on high the pan will be hot to touch, but the water itself absorbs that energy so takes a very long time to actually raise even 1°C.

Liquid cooling is all about transferring that energy in the coolant, not the actual heat itself. So your cpu can be at 90°C, but the coolant will be barely above case ambient temps, and will take somewhere around half an hour to actually get warmer, but will only get to @ 45-50°C at max.

Metals on the other hand, absorb energy exponentially faster than liquids, so when the coolant goes through the radiator, the piping pulls the energy out of the coolant, heats up as a result, transfers that heat to the fins and then airflow from the fans dissipates that.

Is the pump mounted correctly? Nice and tight to the cpu? Not sloppy loose? Sounds like the pump is working correctly but there's no real energy transfer or the fans would make a temp difference. I can't picture so many sensors all going bunk simultaneously, unless there's a paste issue or the pump isn't nearly tight enough to the cpu.
 
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Is the pump mounted correctly? Nice and tight to the cpu? Not sloppy loose? Sounds like the pump is working correctly but there's no real energy transfer or the fans would make a temp difference. I can't picture so many sensors all going bunk simultaneously, unless there's a paste issue or the pump isn't nearly tight enough to the cpu.
Someone else also suggested it may not be mounted correctly but that wasn't the case. I changed the paste anyway and mounted it again. It's tight as it can be.
 

Karadjgne

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Then I'm stumped. There's something I'm not seeing, and thats rare. You shouldn't need to manually have to adjust fans to 100% or even the pump to 100% as the motherboard will do that automatically as soon as temps get beyond 70°C. So something isn't working the way it should, somewhere or bios settings have your voltages so far above spec it's a wonder the cpu still works.

At 3.7GHz on that cpu with that cooler you should be lucky(unlucky) to be hitting 50°C gaming, if that high. The cpu simply doesn't put out enough wattage to create the kinds of heat that'd register the same with 2 different coolers.
 
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Then I'm stumped. There's something I'm not seeing, and thats rare. You shouldn't need to manually have to adjust fans to 100% or even the pump to 100% as the motherboard will do that automatically as soon as temps get beyond 70°C. So something isn't working the way it should, somewhere or bios settings have your voltages so far above spec it's a wonder the cpu still works.

At 3.7GHz on that cpu with that cooler you should be lucky(unlucky) to be hitting 50°C gaming, if that high. The cpu simply doesn't put out enough wattage to create the kinds of heat that'd register the same with 2 different coolers.
I am clueless as well. I tried everything. Currently my assumption is that the new cooler replacement I have been using is not working properly. I contacted Corsair again to see if they can send me another replacement.
 

Karadjgne

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How did you Underclock? Did you manually set the speed or disable turbo but leave voltage regulation on auto? Is the cpu running factory defaults or an actual manual OC or software driven OC like with Dragon Center or OC Genie etc?
 
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How did you Underclock? Did you manually set the speed or disable turbo but leave voltage regulation on auto? Is the cpu running factory defaults or an actual manual OC or software driven OC like with Dragon Center or OC Genie etc?
I manually BIOS OC to 5Ghz using the instructions from Der8auer. To underclock, I set the multiplier to 37 in the bios and lowered the voltage to 1.15v. I didn't change anything else from the original 5GHz instructions.
 

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