Improving temps - high temps at factory clock, mini-ITX build

[catherine.lee.ball]

Recently I built a somewhat modified version of this mini-ITX build. The actual parts I ended up using are in this Google sheet, or in this gist with some installation notes. The TL;DR of the build is an air-cooled mini-ITX case with a factory clock i7 8700k and no dedicated GPU.

Prime95 stress test on Win10 using small FFTs for high heat, monitored with hwmonitor:

• 
  ■ ~ 30° C idle
  ■ 96° C max @ 1hr

I was afraid the M.2 drive was creating too much heat, so to avoid having to physically remove the disks and test again, I ran the same tests from an Ubuntu live USB, using mprime monitored by lm-sensors:

• 
  ■ ~ 30°C idle
  ■ 92°C max @ 30min

I was afraid that maybe the CPU fan or case fan had failed despite hwmonitor reporting their running speeds, but peeking in the case they were definitely running.

Some other suspects I'm considering but unsure of:

• 
  ■ Should I re-seat and re-thermal-paste the CPU fan? (although idle temps were ok)
  ■ Should I try re-running the cables? (not much space to work with, but there's some hanging out between the case fan and CPU)
  ■ Could using integrated graphics be generating more heat than if I had a GPU? (although idle temps were good and CPU usage low at idle)
  ■ Try and jam a water cooler in? (only room for a single 120mm fan though, and the radiator would be a tight squeeze)
  ■ Reverse the case fan? (it pulls air in currently, positive air pressure in case, but maybe exhausting for negative temp would be better?)
  ■ See if I can return the tiny case and motherboard and get something with more space?

If it's helpful, here's CPU info from CPU-Z. I used Noctua NT-H1 thermal paste, applied in small ~2 or 3mm circle to the middle of the processor.

Any ideas why this is happening are appreciated! Let me know if there's other troubleshooting I should try, or more info you need. I was hoping to do a modest overclock, but I'd honestly be happy at this point if I could get factory clock at max load closer to 80C.

 

[marksavio]

i believe your temps are just fine. the noctua CPU fan is more on the low-end aircooler for a CPU of that level. anything with more than 4 cores will get hot really quick. even gets hotter when youve set it to sync all cores.

the popular coolers for the 8700k are the

• noctua-dh15/s
  nzxt kraken x52/x62
  corsair h80i/h110i/115i v2
  be quiet! dark rock pro 3 (cheapest and unstable temps)

for now you will have to try this in your BIOS to control your temps with the cooler you have :
* enable the XMP profile of your RAM
* disable Multicore/Turbo Enhanced
* set it to per core, and downclock the last 2 cores by 1~2 (e.g. 48,48,48,48,47,47)
* set your AVX offset to 1~3 (e.g. highest target turbo is 48. minus by an offset of 2. will make your cores clock down to 46) AVX commands are used mostly used by non-gaming softwares/windows apps. some games may use it as well. but during most games, it will max to your set turbo/OC speed.

also set your windows OS powerplan to balanced mode, to alleviate stress on your CPU. and for your GPU go to nvidia control panel. 3d graphic settings. global. power mode to adaptive/high. this will ensure your GPU will run max while youre playing games.

if you have thermal paste like these or better, then you are fine

• arctic silver 5
  noctua nt-h1

 

[geofelt]

Your case supports a 61mm tall cooler.
What you have is as good as it is going to get.

My best suggestion is to get more air into the case.
I think you can mount a 140mm fan which will move more air.
If you can buy one with higher rpm, you can greatly increase the airflow.
1300 rpm is about what you will get with the noctua 140mm fans. That is plenty good.
But, if you decide you need more, there are some very aggressive high rpm 140mm fans available.
The price you pay will be higher noise.
But, to make room for a 140mm fan, you need to limit your graphics card length to 9,5"

one with a blower cooler that gets the gpu heat directly out the back of the case will be 10.5"
Something like this:
https://www.newegg.com/Product/Product.aspx?Item=N82E16814487357

There are mini GTX1080 cards that will fit, but they are not blower types.
If you want a full length graphics card, you may have to pay the price with a very high rpm front 120mm intake.
Your 30c. idle temperature tells me that your cooler is mounted well and is functioning.

One might be tempted to install an aio cooler with a front mount radiator drawing air in.
That would cool your cpu better, but the down side is that your graphics card and motherboard will be fed hot air and run hot.

You will need the cpu cooler fan to run at somewhat high speeds.
Do not use the included noctua low noise adapters.

Not to worry.

Realize that synthetic tests will generate more heat than you will normally use.
The processor will slow down or turn off if it detects a dangerous temperature.
That is around 100c.

 

[catherine.lee.ball]

Thanks for the info marksavio and geofelt! You're right, under load testing with World Community Grid on BOINC, and the blended Prime95 stress tests had less bad temps, and real world use will probably be even lower.

Thanks for the cooling suggestions too! I might revisit overclocking the CPU (and maybe even a fancier cooler) after I find a GPU. I'll definitely post if I run into any issues, or before considering buying any new hardware. I'm very happy with how quiet the machine makes right now, so I'll probably try to stick with the current cooling setup even if it means keeping things at stock clock.

Cheers!