Processor for ROCK (8th generation)

[aKnyght]

just heard back from the chassis manufacturer re: TDP…

“Our test shows high TDP CPU does not run hotter doing the same task especially when their clock speed is the same.”

…makes sense.

[Xekomi]

does the TDP matter?

Yes, it very much does.

Cases are designed to dissipate a certain amount of heat - i.e, for a given max TDP, that’s why some Akasas don’t officially support i7 NUCs. Your environment (no AC in the summer…) matters as well. Bigger cases, with bigger heatsinks, dissipate more heat - it’s physics. Stick to what the case’s manufacturer recommends, within reason of course - don’t stick a 95 watter inside a case specced for 65w, but don’t sweat it too, too much if you’re putting a 75 watt CPU inside it, and you’ve got your AC set to “Russian winter” type of thing. You’re not running prime95, 24/7.

[aKnyght]

thanks for all the help and information!!

in looking at the processors currently available for the h370 chipset, there are several i5 and i3 processors that have a higher base frequency than the i7-7567U processor in the roon specified i7 NUC.

i7-7567U… 3.5GHz (4.0GHz max) / 2 core, 4 threads / 28W TDP

i5-8600K… 3.6GHz (4.3GHz max) / 6 core, 6 threads / 95W TDP
i3-8350K… 4.0GHz (4.0GHz max) / 4 core, 4 threads / 91W TDP

the i3-8350K would seem to meet the requirements implied by the roon specified i7 NUC processor for large libraries and DSP use… and it costs quite a bit less.

any comments / thoughts / recommendations here regarding the i3 or i5 suitability for my use case in the OP would be very welcome!

one additional detail - my library is pretty small: cannot imagine it ever exceeding 2,500 albums.

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also, i am confident the higher TDPs are not an issue in a well designed fanless chassis, particularly given:

1. intel defines TDP as: “…the average power, in watts, the processor dissipates when operating at Base Frequency with all cores active under an Intel-defined, high-complexity workload.”

2. roon DSP, including upsampling, is not parallelized and runs on one core (correct me if i am wrong on this point).

[Xekomi]

one additional detail - my library is pretty small: cannot imagine it ever exceeding 2,500 albums

Neither of the “K” processors meet ROCK requirements, because they’re not in NUCs

If you want something that’s officially supported, pick up one of the recommended NUCs, slap it into an Akasa case, add a fast NVMe drive for the database and a suitable data drive, done. Here’s a side-by-side that includes single core speeds.

If you’re going to go the not-officially-supported MOCK route, an i3 should do the trick. Here’s that comparison with the recommended i7 NUC. There are several fanless case options there, depending on your design sensibilities, dexterity with a screwdriver, and desired level of finishing.

At the end of the day, it depends on your priorities: you’re going to have to pick two out of “faster, cheaper, officially supported”, and that’s a choice no one else can make for you.

[ScreenMachine (James)]

device will be on the audio rack – for the purposes of optical-isolation and, thereby, removal of all upstream electrical noise, the device will connect to the network via wi-fi and then directly to the USB DAC. i have had spectacular results with this topology in my current set-up.

could move the device into another room when / if i install a fiber network connection to the audio rack, but would then have to get a FMC + the associated cables and power supply… so, not sure i really gain anything.

keeping my eyes open for a suitable DAC with an SFP port to accept a fiber input. but i think it will be a while before they are readily available.

If you want to achieve optical isolation but place the ROCK in another room, you might want to check out one of the opticalRendu/opticalModule solutions here

[wklie (Peter Lie)]

does the TDP matter? for a fanless chassis, is there a general TDP spec not to exceed?

Yes. Visit the Akasa web site and check out the fanless NUC compatibility list and you’ll see they only support fairly low TDP CPU. With a higher TDP CPU it gets really difficult and expensive to make a proper fanless case.

There were overheating cases with both fan and fanless chassis for NUC7i7BNH 28W TDP. Although not intuitive, this TDP figure can be exceeded in practice. This review measured it at 58.5W:

Kaby Lake i7 NUC Review 4/4: Fan, Power, Linux, Conclusions (NUC7i7BNH)

Also check out this thread:

Cirrus7 fanless i7, will it work?

The choice of CPU is related to performance needs (e.g. DSP) and TDP, especially if you use a LPS or a fanless chassis. ROCK compatibility, if I’m not mistaken, is more concerned with drivers especially Ethernet. More on LPS: If one is intending to use a 36W LPS, then a 28W TDP is too high just for the CPU, since there are other things that need the power.

And this good example:

The Best NUC for ROCK?

While I prefer to have my Roon Server outside of the listening room (like I had in my previous house), my current setup in my apartment needs to have my Roon Core inside my listening room unfortunately. So I’ve picked up the NUC7i7DNHE with an Akasa Plato X7D fanless case. It took a few hours to put together because I’m extremely slow but also because I triple checked all connections because I never want to open it again. The beauty with this is not just the fanless case with no moving parts …

My advice is to forget about arbitrary high power CPU and use only a NUC that’s proven by other members in this forum.

[wklie (Peter Lie)]

roon DSP, including upsampling, is not parallelized and runs on one core (correct me if i am wrong on this point).

It uses two threads (cores) per zone if you enable Parallelize Sigma Delta Modulator. Other threads are still needed for other tasks like analysis, UI and library management, etc. So all cores can be used.

[aKnyght]

peter – as always, thanks very much for the help!

With a higher TDP CPU it gets really difficult and expensive to make a proper fanless case.

i would use a NUC except that my specs call for a mini-ITX motherboard having a PCIe expansion slot (h370 or h310 chipset). so now, i am just trying to find the CPU with the best performance in terms of single-zone DSD upsampling that will not exceed the thermal management capabilities of the case.

i am using an HDPlex H3 V2 case which has a more robust heatsink system than that of the akasa and can, hopefully, accommodate a somewhat higher TDP CPU.

one other CPU that might possibly work is:

• i3-8300T… 3.2GHz (3.2GHz max) / 4 core, 4 threads / 35W TDP

or even:

• i7-8700T… 2.4GHz (4.0GHz max) / 6 core, 12 threads / 35W TDP
• i5-8600T… 2.3GHz (3.7GHz max) / 6 core, 6 threads / 35W TDP

however, their base speeds might be too low for dsd512 upsampling? if so, i could always turn on multi-threading and/or just live with dsd256 or even dsd128 upsampling.

any thoughts the “T” CPUs, especially the i3, would be great.

[cuco (Tobias Klenk)]

i would go with a i5-8400 or i5-9400. Why? Basically these cpus use all the same power in idle.
And the i5-8400 and the 9400 are very comode in power use when under heavy load. But have high enough base clock speeds and cores. Have a look here. sorry it is german but the table should be readable. Tey use a 1080ti but the results are all comparable.
Right now i have to make the same decision as you.
Buy a nuc or build my own rig? I tend to go with a Asrock deskmini 310 and a 8400 cpu. Should be arround 12w idle and when asking for more power it is ready. and when it is not in heavy use these cpus wont consume more then the Tmodels.
One more thing you should think about. Cpus with more power/clockspeed tend to do the same work in less time. So they can go to lower power states earlier. Or they do it with less clockspeed.
And when they get too hot, they throttel down. And wheter you use a 35w or a 65w modell. the temp limits are the same. When the cooling system can handle it it makes absolutely no sence to use a T-Model.

[wklie (Peter Lie)]

I speculate (but cannot be sure) that any of your listed CPU should do fine with DSD512 upsampling as long as you turn on Parallelize Sigma Delta Modulator. (Our i5-6600 does.)

For a non-fanless non-ROCK setup, I’d just go with the CPU that offers a good cost/single thread performance with no less than 4 core, and compatible with the motherboard I choose.

For a fanless non-ROCK setup, the fanless chassis becomes a limiting factor - this determines whether you want to sacrifice performance or increase cost by going with a T CPU. If you use a LPS, the maximum power consumption also needs to be determined carefully. Considering the added heat and power, more cores are not necessarily better.

For a fanless ROCK setup, just get a NUC7i7DNHE.

[aKnyght]

peter - thanks for the info and insight on the three options! i think i now have a good handle on this.

the T CPUs look to be quite similar in price but with the noted power / performance tradeoff.

interestingly, this tradeoff in the i3-8300T is rather small with the base speed still at 3.2GHz for 35W. also, the frequency / TDP can be down-configured to 2.5GhZ / 25W which is closer to being on par with the NUCs. looks like the best and a good option for my purposes.

unfortunately, the T CPUs are not due back in stock until late march at all the usual online sellers… so, on hold for a while unless anyone knows of another source?

[Mikael_Ollars]

If you’re aiming to upsample to DSD512 I’d say you will need to go for something more powerful than an i3, whatever generation. But, one the other hand, the Intels Speed-Stepping and throttling is very well executed in the 8th gen Core processors.

In the first post of this thread you can find some real world examples of processor and hardware performance, however only up to DSD128:

Performance Matrix Roon Server

I know there are recommendations available for chosing hardware, but there are quite few performance reports from real world examples. Are there more people than me who wants to know what they can expect from, say, a Gen 6 i5 NUC running ROCK compared to an older PC with an Intel Core i5 3470? If so i suggest that we create a matrix within a limited set of boundaries to keep it simple and reasonably comparable and understandable. The only way i know of getting performance figures out of roon is…

I have added most of these and just to clarify, the tests using my i7 8700 doesn’t seem too impressive by only judging from the figures in the spreadsheet. However, when upsampling to DSD128 the computer was just barely idling and the Speed stepping throttled the clock frequency way down.
(Which can be seen on then power consumption…)

[aKnyght]

If you’re aiming to upsample to DSD512 I’d say you will need to go for something more powerful than an i3, whatever generation. But, one the other hand, the Intels Speed-Stepping and throttling is very well executed in the 8th gen Core processors.

given fanless, one is pushed to CPUs with low TDPs which in turn makes the intel T CPUs the best (only?) choice. and, from the discussion here the consensus seems to be that for DSD upsampling one wants a CPU with a high single core frequency…

of the three T CPUs available the i3 would seen to optimize on power / single core speed:

• i3-8300T… 3.2GHz (3.2GHz max) / 4 core, 4 threads / 35W (25W) TDP
• i5-8600T… 2.3GHz (3.7GHz max) / 6 core, 6 threads / 35W (25W) TDP
• i7-8700T… 2.4GHz (4.0GHz max) / 6 core, 12 threads / 35W (25W) TDP

in any event, the i3 should otherwise more than meet my needs and if/where it falls short on dsd upsampling i will have to make do.

would be very interested to get your thoughts here.

[Mikael_Ollars]

for DSD upsampling one wants a CPU with a high single core frequency…

I’m not entirely sure this reflects the real world scenario. If you use “Parallelize Sigma Delta modulator” in DSP Upsampling settings i seem to recall all cores of the i7 8700 were being utilized evenly.
(However, at DSD128 tasks they were nowhere near their max frequencies)
If i had a DSD unit that could do better than DSD256 i’d be glad to try it out for you and measure power consumption. (I have DSD256 options though)

[aKnyght]

If you use “Parallelize Sigma Delta modulator” in DSP Upsampling settings i seem to recall all cores of the i7 8700 were being utilized evenly.

this is interesting… and, is at odds with the consensus above - esp:

It uses two threads (cores) per zone if you enable Parallelize Sigma Delta Modulator. Other threads are still needed for other tasks like analysis, UI and library management, etc. So all cores can be used.

maybe roon can comment on the number of cores used both with and without enabling Parallelize Sigma Delta Modulator. also, maybe roon can comment on this thread in general with respect to which CPU characteristics are most important for a fanless ROCK to be on par with a nucleus+ …maybe, a set of minimum specs which must be met?

given that intel is continually updating / replacing their CPUs and that the ultra-low-power “U” CPUs are not available as a stand alone purchase as far a i know, such information would be helpful on an ongoing basis to the DIY community here.

not sure who to ping here but maybe @danny or @support can direct this to the best place.

[wklie (Peter Lie)]

DSD512 - Is this even possible? [yes, just needs more cpu]

The majority of systems used to run Roon have 2 cores / 4 threads or less. NUCs are the typical archetype. We monitor these stats on an ongoing basis to drive these decisions. There is overhead associated to splitting/joining work across cores. It is most efficient to run things on 1 core if they fit there. We enabled the split to 2 cores as a technique for making extreme DSD upsampling cases workable. Unnecessary multi-core processing has other have negative consequences for the overall user…

[aKnyght]

thanks again peter! …question answered.

[wklie (Peter Lie)]

of the three T CPUs available the i3 would seen to optimize on power / single core speed:

• i3-8300T… 3.2GHz (3.2GHz max) / 4 core, 4 threads / 35W (25W) TDP
• i5-8600T… 2.3GHz (3.7GHz max) / 6 core, 6 threads / 35W (25W) TDP
• i7-8700T… 2.4GHz (4.0GHz max) / 6 core, 12 threads / 35W (25W) TDP

If you are determined to buy only from this set of choices and assume your fanless chassis is thermally capable to handle any of them: For DSP purpose in addition to upsampling, get the i7. Otherwise i5 seems to be a good cost/performance choice, as the 0.5GHz increase from i3 to i5 costs less than the 0.3GHz increase from i5 to i7.

[Craig_Palmer]

I’m having trouble finding the option to turn on Parellelize Delta Sigma Modulator in the new 1.6 UI. Where is it now?

[aKnyght]

thanks for the recommendation!

i am not necessarily determined to buy a T-designation CPU; however, they are the processors with the lowest TDP i can find that are available for stand-alone purchase – as far as i know anyway.

other suitable CPUs are available with 65W TDPs. maybe they are more “efficient” making their higher TDP less of an issue… but, this is way beyond my knowledge of the subject.

its also possible i am trying to fit a square peg in a round hole… maybe a NUC in another roon with a fiber run to an FMC or an opticalRendu just before the DAC is better and, perhaps, the path of least resistance?