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Passive cooling with Intel's Core i9-9900K CPU

By Shawn Knight · 14 replies
Mar 12, 2019
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  1. There are many approaches to take when building a PC. At the top of my list of priorities is silence. My current system consists of mid-range (for its time) hardware in an oversized case outfitted with large, slow-spinning fans and a solid state drive. There’s a massive twin-tower heatsink on the CPU that’s overkill for all but the highest-end of chips. The rig is still audible, but just barely.

    While still sufficient for my needs, I’ve dreamed of building a truly high-end rig that is entirely passively cooled. Maybe I’ll get around to it someday but in the meantime, I can enjoy watching others do the same.

    YouTuber der8auer recently set about to testing the Arctic Alpine 12, a passive heatsink made from a single chunk of aluminum. Visually, the heatsink is nothing to write home about. In fact, it looks more like an old-school cooler than something you’d use to cool a modern CPU… much less, an Intel Core i9-9900K.

    In fairness, this isn’t really the passively cooled system of my dreams (nor is der8auer making it out to be). The system isn’t mounted inside a case but rather, sits out in the open air. The video card also has a fan on it and the Seasonic PSU also appears to be actively cooled. Still, he’s using a fanless heatsink rated to handle a TDP of just 47W to cool an i9-9900K.

    Sitting at the desktop in Windows, the average CPU core temperature was around 49 degrees Celsius but when running Cinebench R20, it immediately shot up to around 100C. Further stress testing with Prime 95 revealed the chip is being throttled down to around 2,600MHz with power consumption of just 54W.

    With a bit of manual tweaking in the BIOS, der8auer was able to run Far Cry 5 at 1080p with an Nvidia GTX 1050 Ti at around 40 frames per second with a CPU frequency of 3.6GHz at 0.925v. CPU utilization while playing hovered between 15 to 30 percent. CPU temps stayed around 70C to 75C.

    Permalink to story.

  2. Vulcanproject

    Vulcanproject TS Evangelist Posts: 695   +949

    Interesting but yes, of course you can passively cool a modern 8 core CPU if you count undervolting and underclocking it while having just 30 percent peak load. I personally don't.
    Steve, Bluescreendeath and Raytrace3D like this.
  3. Nobina

    Nobina TS Evangelist Posts: 1,844   +1,351

    It also works well if your computer is turned off.
  4. nnguy2

    nnguy2 TS Booster Posts: 25   +25

    [/QUOTE]It also works well if your computer is turned off.[/QUOTE]

    you magnificent bastard. lol
    Raytrace3D likes this.
  5. Dimitrios

    Dimitrios TS Guru Posts: 395   +267

    My brother has an AMD Phenom X 4 965BE at 3.4GHZ with a broken heatsink fan and it's been about 5-8 months with just his side case open and his pc runs fine lol! He had it overclocked to about 3.8GHZ and keep shutting off. I looked into his BIOS and temps were 85c and climbed to 102C within 30 secs! I left it at 3.4GHZ ( stock) and it's fine again. That's 225F! Can I scramble eggs on it? ;-)
    JaredTheDragon likes this.
  6. QuantumPhysics

    QuantumPhysics TS Evangelist Posts: 1,003   +732

    I have the i9 7980. You'd be insane to try to use one of these without liquid cooling. Forget fan cooling.
    Dimitrios likes this.
  7. Raytrace3D

    Raytrace3D TS Addict Posts: 95   +100

    I had my Threadripper 2950X on a single radiator for a few months and it ran hot just sitting idle. Moved it to a 3 rad and it runs nice and cool and quite now. Don't know if it's possible to run on all passive cooling.
  8. dogofwars

    dogofwars TS Addict Posts: 172   +67

    I was surprised when my water pump was off because of a loose power cable and I was running all cores of my 2700X to the max and it ran at 3.8Ghz. So basically the only thing that was cooling off the processor was the waterblock and the idle water in the block and all that at 66 Celsius. I presumed it was like that for a while since the temp history was 66~ Celsius for more then a day.
    Dimitrios likes this.
  9. Dimitrios

    Dimitrios TS Guru Posts: 395   +267

    What was the temp in that room?
  10. Knot Schure

    Knot Schure TS Addict Posts: 226   +97

    A who-cares article if ever I saw one.
  11. toooooot

    toooooot TS Evangelist Posts: 725   +343

    Good question. When I play ME andromeda (most demanding game at the time it seems)
    my liquid cooling PC can go to just 40 or near 48 depending on the temp in my room.
    I think there is a possibility for this passive cooler to actually throttle in summer under load.
  12. urbanman2004

    urbanman2004 TS Booster Posts: 80   +27

    No reason to buy a damn near $600 CPU when there's constraints such as passive cooling keeping the user from maxing its untapped power potential
  13. dogofwars

    dogofwars TS Addict Posts: 172   +67

    Was in summer, somewhere around 25 C room temperature.
    Dimitrios likes this.
  14. captaincranky

    captaincranky TechSpot Addict Posts: 14,696   +3,848

    So the bottom line is, the 9900 was able to do about as much computing as the i3-Something, for which the cooler was designed, before it overheated.

    (It probably would have done better if he hired a Geisha to fan it).

    Here let Mulan help you with that:


    (What can I tell you, a comic book thread deserves a comic book Geisha).
    Last edited: Mar 14, 2019
  15. ypsylon

    ypsylon TS Booster Posts: 155   +43

    In general it is quite silly question. Provided you have enough space you can cool in a "passive" way any cpu.

    On the other hand from purely science standpoint, any kind of radiator is an active cooler - that's why I "" passive word above. Fan on it doesn't cool anything. It only improves heat transfer into the ambient. Radiator always actively cools piece of electronic. It moves heat from a silicon away to the environment. Fan has literally 0 cooling capacity without radiator. Physics 101.

    Common misconception, which unfortunately is multiplied billions of times every day, month, year around the world.

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