CPU Under-clocked 8700k... Temperature vs Performance?

jimmivalentino

Efficiency Noob
Original poster
Dec 23, 2017
7
1
So this will be my first build. I work in audio and have been interested in doing a build for a while now, so I can get better single-thread performance than Apple will provide. I do a lot of off-site work, so I was looking at the NFC S4M because of the extreme portability factor. Problem is, I want to cram an 8700k into it and it seems wayyy too hot to fit in a case like that.

So with that being said... do I underclock/volt it or do I look at different silicon? Am I more likely to get better performance out of this as an underclock or a different chip that runs colder under stress?

Side note: I’m not doing any gaming or video stuff with this build, so waste heat from GPU shouldn’t be too much of an issue... might even ride out the integrated graphics in the interim, not sure yet...
 

ikjadoon

Cable Smoosher
Dec 23, 2017
9
5
Is noise a concern because it's audio work? How CPU intensive is your software--is it actually just single-threaded? If it's actually just stressing a single thread, you'll never hit the actual TDP (which assumes a 6-core, 12-thread workload).

FWIW, I run a stock clock/volts i5-8600K (95W TDP) on the stock Intel cooler in a small, but well-ventilated 5.75L case (about 1.5L larger than the S4 Mini) and highly-multithreaded Handbrake puts the CPU at around 75C, which is still 25C+ from TjMax.

On your bigger question: a good point. I want to say silicon is silicon, so any desktop-class Coffee Lake CPU running at specific voltages/clocks/cores/threads should have very close heat output. It does become a question of price/performance (if you're underclocking), but I can definitely see the appeal of an i7-8700K.

Maybe interesting benchmarks to read on power/heat:

http://www.tomshardware.com/reviews/intel-coffee-lake-i7-8700k-cpu,5252-12.html
 
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jimmivalentino

Efficiency Noob
Original poster
Dec 23, 2017
7
1
Is noise a concern because it's audio work? How CPU intensive is your software--is it actually just single-threaded? If it's actually just stressing a single thread, you'll never hit the actual TDP (which assumes a 6-core, 12-thread workload).

FWIW, I run a stock clock/volts i5-8600K (95W TDP) on the stock Intel cooler in a small, but well-ventilated 5.75L case (about 1.5L larger than the S4 Mini) and highly-multithreaded Handbrake puts the CPU at around 75C, which is still 25C+ from TjMax.

On your bigger question: a good point. I want to say silicon is silicon, so any desktop-class Coffee Lake CPU running at specific voltages/clocks/cores/threads should have very close heat output. It does become a question of price/performance (if you're underclocking), but I can definitely see the appeal of an i7-8700K.

Maybe interesting benchmarks to read on power/heat:

http://www.tomshardware.com/reviews/intel-coffee-lake-i7-8700k-cpu,5252-12.html

Hey, thanks for that... did read that Tom's Hardware article a couple weeks ago but lost it. I think it was probably my main reason for posting this in the first place, because of how hot the CPU ran when under load in their tests and how it throttled at stock clocking with compressor cooling.

Yes noise is a big concern, but equally is overheating. Live Audio processing is one of the most intensive tasks you can throw at a CPU, and I don't want my desire for portability to be at the expense of reliability. I've had my Mac CPU throttle when I'm working remotely with a client, and I have to say to them, 'look we have to bounce down things and then wait 20 minutes or so to start working again'. So it's about finding a balance which will give the most performance and the lowest likelihood of overheating + becoming too noisy.

The idea of the 8700k was that the single-thread performance bests even Intel's non-consumer CPUs and it is very affordable. This is one of my main reasons for coming back to Windows, for maximum single-thread performance that Apple doesn't offer hardware for. The audio applications I use, and moreso just audio processing in general, can't utilize multiple cores + threads as much as I believe other workstations tasks like rendering etc can, because the audio is summed in real time and that process takes place on a single thread. Other tasks within the application can be, but these tasks are quite minimal compared to the task of live processing, and that is a big thing I want to improve with this build over my Mac, so that I'm not having to bounce things to disk when they still need more work, which wastes time and clogs up my SSD, just to get a bit more performance.

The thing about single-threading not hitting the actual TDP is interesting - can't believe I never considered that before. Would be interesting to see how different it actually is in practice with the monstrous CPU draw of the applications I'm running... because I have no doubt that even without underclocking/volting I'll be running the first thread into the ground, but probably won't touch the others that heavily at all, so the fact that you are getting those temp. results even with an app like Handbrake is interesting. Might have to find someone locally with an 8700k to test it out.

Out of interest, what case are you using?
 

ikjadoon

Cable Smoosher
Dec 23, 2017
9
5
Hey, thanks for that... did read that Tom's Hardware article a couple weeks ago but lost it. I think it was probably my main reason for posting this in the first place, because of how hot the CPU ran when under load in their tests and how it throttled at stock clocking with compressor cooling.

Yes noise is a big concern, but equally is overheating. Live Audio processing is one of the most intensive tasks you can throw at a CPU, and I don't want my desire for portability to be at the expense of reliability. I've had my Mac CPU throttle when I'm working remotely with a client, and I have to say to them, 'look we have to bounce down things and then wait 20 minutes or so to start working again'. So it's about finding a balance which will give the most performance and the lowest likelihood of overheating + becoming too noisy.

The idea of the 8700k was that the single-thread performance bests even Intel's non-consumer CPUs and it is very affordable. This is one of my main reasons for coming back to Windows, for maximum single-thread performance that Apple doesn't offer hardware for. The audio applications I use, and moreso just audio processing in general, can't utilize multiple cores + threads as much as I believe other workstations tasks like rendering etc can, because the audio is summed in real time and that process takes place on a single thread. Other tasks within the application can be, but these tasks are quite minimal compared to the task of live processing, and that is a big thing I want to improve with this build over my Mac, so that I'm not having to bounce things to disk when they still need more work, which wastes time and clogs up my SSD, just to get a bit more performance.

The thing about single-threading not hitting the actual TDP is interesting - can't believe I never considered that before. Would be interesting to see how different it actually is in practice with the monstrous CPU draw of the applications I'm running... because I have no doubt that even without underclocking/volting I'll be running the first thread into the ground, but probably won't touch the others that heavily at all, so the fact that you are getting those temp. results even with an app like Handbrake is interesting. Might have to find someone locally with an 8700k to test it out.

Out of interest, what case are you using?

No worries; the article popped in my mind.

Er, wait: that article actually doesn't show stock clocks throttling, but it's also high-end water / below-ambient cooling. More so, their benchmarks stress most or all of the 12 threads simultaneously.

Got it, yes. This makes sense: the i7-8700K rips through single-threads faster than anything else at stock clocks. Unrelated: if it's mainly single-core, you do have a kind of time-intensive route of OC'ing an i3-8350K/i5-8600K on just Core 0 (you can set overclocks per core on Z370). It's time-intensive for testing for stability and if it's a production environment, I'm much less eager to take the time, but it's definitely possible to reach i7-8700K stock performance on a single-thread with cheaper CPUs.

Exactly: with just a single-thread stressed, the chip won't get anywhere near its TDP. For shits and giggles, I set Handbrake to a single core affinity (i.e., only core 0 pegged @ 100%) for a ~5-minute 3Mbps 1080p H.264 clip: average temp was 55C with a peak of 58C and this is the stock Intel cooler with some higher-end TIM, but nothing like liquid metal. The Turbo Boost bounced between 4.1GHz and 4.3GHz as I had a few other programs opened; and, right: still on the stock clocks/volts i5-8600K.

For noise, I'd not choose the Intel stock cooler which definitely winds up on six-core workloads--eh, it doesn't even come with the K-series CPUs any more; I had a spare one from an old i5-4670K, so probably an easy decision for a new system haha.

Oh, right! I'm using a Lan Gear Effy for the peculiar situation of wanting a single GPU slot in a pretty tight mini-ITX case that cost less than $80. It does have pretty decent cooling chops, too, though which helps the temperatures.

I would imagine an i7-8700K would performs similarly, but likely a tad hotter as it's a single-core boost of 4.7GHz instead of 4.3GHz and a local test is always definitive.
 

Thauner

Average Stuffer
Oct 5, 2017
63
26
Im doing audio work myself.
Just build a very small and portable computer for that. But after alot of talking about 8700k and alternatives I went with the 8700 non k. Mainly because I don't want to overclock, and the cpu is only 65w.

I have it in a streacom case, one of the smallest cases I liked. But no space for a graphic card. I've moddet the top for better temps, and it works great with my noctua nh-l9i. But still wished to have an option for even better cooling, coffee lake do run hot!

https://ibb.co/dJBKmb
 
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jimmivalentino

Efficiency Noob
Original poster
Dec 23, 2017
7
1
Im doing audio work myself.
Just build a very small and portable computer for that. But after alot of talking about 8700k and alternatives I went with the 8700 non k. Mainly because I don't want to overclock, and the cpu is only 65w.

I have it in a streacom case, one of the smallest cases I liked. But no space for a graphic card. I've moddet the top for better temps, and it works great with my noctua nh-l9i. But still wished to have an option for even better cooling, coffee lake do run hot!

https://ibb.co/dJBKmb
That case is the thing of my dreams. If only I could cool it :(

How are you finding the 8700 in that setup for audio work? What work are you doing?
 

Thauner

Average Stuffer
Oct 5, 2017
63
26
That case is the thing of my dreams. If only I could cool it :(

How are you finding the 8700 in that setup for audio work? What work are you doing?

Well it was my dream to, but I was fully okay with the fact that I had to mod the top for more air flow. Thinking about only running with one fan wich is the cpu fan.

I'm using fl studio, wich also is heavy load on singlecore. When I have my biggest projects open and running, the cpu runs at good temps, boosting to 4.3-4.6ghz on one core or 4.3 on all. Temps at highest load at 50-65c. Overall I'm very impressed with the chip when I'm doing audio work. Considering I came from a 6700, and I feel the performence boost alot.

I would never buy a k model unless I wanted to overclock. I'm no expert, but can't imagine that you would feel the difference in boost speed with 8700k over the nok k. I would rather save the power and heat.
 
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jimmivalentino

Efficiency Noob
Original poster
Dec 23, 2017
7
1
Well it was my dream to, but I was fully okay with the fact that I had to mod the top for more air flow. Thinking about only running with one fan wich is the cpu fan.

I'm using fl studio, wich also is heavy load on singlecore. When I have my biggest projects open and running, the cpu runs at good temps, boosting to 4.3-4.6ghz on one core or 4.3 on all. Temps at highest load at 50-65c. Overall I'm very impressed with the chip when I'm doing audio work. Considering I came from a 6700, and I feel the performence boost alot.

I would never buy a k model unless I wanted to overclock. I'm no expert, but can't imagine that you would feel the difference in boost speed with 8700k over the nok k. I would rather save the power and heat.

Those temps are very reasonable. How is noise?

Going with the K would be for the flexibility + availability. Can't easily get 8700s here is the biggest issue. I'd probably be taking the 8700k down to 8700 clock to bring down temp a bit anyway.
 

Thauner

Average Stuffer
Oct 5, 2017
63
26
Those temps are very reasonable. How is noise?

Going with the K would be for the flexibility + availability. Can't easily get 8700s here is the biggest issue. I'd probably be taking the 8700k down to 8700 clock to bring down temp a bit anyway.

Okay, that sounds like a plan. Still, for me it sounds crazy to downclock the k model, why not buy the i5 then?

There is low to no noise for me, and the case is 50cm away from my head. Only fan spinning is the noctua nh-l9i, and it's spinning around 800rpm most of the time. 1200-1800 when it gets hotter. But still, damn low noise compared to many other fans i ever testet. Even at high speed it has a much more soft noise than other brands.