Build ideas needed - semi passive, semi tornado cooled

PaulCa

PaulCa

PaulCa

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3 May 2018
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604
The target:

When the machine is doing light desktop duties it should be completely silent, almost entirely passively cooled. *caveats.

When the machine is working hard it will be permitted to get pretty loud, as long as it is not unnecessarily loud.

Current setup:
Kraken x73 CPU cooler 360 rad, NZXT fans.
Alphacool Aiswolf GPU cooler 360 rad, alphacool fans.
Fractal design 140mm DC case fans <- Free to good home!
CF Hero 8, 5800X, 3080 (eagle), 32Gb, Firecuda 500Gb m.2 gen 4, Evo850 500Gb, TeamGroup 1Tb Steam drive.

Previous approach on a similar build:
Allow the rad fans to spin at idle speeds (corsair and nzxt pwms) for idle airflow. CPU front intake. GPU top exhaust rads.
Case fans stop on idle. 2x140mm provide filtered intake air for the GPU exhaust radiator in tandem with the GPU rad fans. Provide directed exhaust under high CPU load over the VRM area with a 140mm exhaust fan in tandem with the CPU rad intake fans.
This remains mostly silent on desktop, sounds like a rack server on full gaming load. Temps all under 60*C. GPU stays under 50*C for best boost clocks. Minimal dust collection after 3 years. Fans are still silent and low noise running after 3 years heavy use.

Issues:
Having gone from 240mm rads to 360mm rads, the idling fans on the front rad are loud enough and I haven't fitted the GPU cooler yet!
I'd like to consider full stop on all fans.
Balancing airflow is more difficult with 360s. Previously I was balancing 2x120mm exhaust fans with 2x140mm filtered intake fans to prevent dust inhalation. With a 360mm rad I would need 3 intake fans, which means borrowing a CPU rad fan or two to help... which means more noise than necessary.

Option:
Repeat the same build as before. Just spend additional money on better SP 0db regime case fans for intake. Nutuca or EK fans for the rads to keep their idle speed silent, or stop altogether.

More thought:
The primary sources of heat are the CPU chip and the GPU chip. Those are water cooled, so getting that heat OUT of the case promptly is the best option. With the GPU being an exhaust radiator that effectively removes that heat out of the case, but presents us with the balanced intake problem to prevent dust. Using the CPU radiator fans at the same time for intake for some reason does not appeal, they make more noise pushing through the radiator which is un-necessary when intake case fans are quieter. Similarly when the CPU is under high load it's intake air is warm, not ideal for helping to cool the memory and VRMs which will also be getting hot under that load, so 'steering' fans are needed.

Option:
Using 120mm radiator mounting brackets, a drill, some grommets and a few nuts and bolts, mount both radiators to the back of the case with dust filters. Use fans that stop on them so they can just convectively cool under light load. That makes solving the case fan issue much, much easier. With 2 intake, and 1 exhaust dynamically tuned based on load to keep the most likely heaters (GPU backplate, VRMs, X570 chipset, M.2 drive, DIMMs cool(er). Without all that radiator heat and airflow inside the case keeping those cooler should be easier.

Either way it looks like I'm going to be spending a LOT on fancy fans :(

Any thoughts? Note, yes I have seen the OTS solutions, but firstly they are expensive, secondarily I already have 99% of the work hardware for 2x360 radiators, CPU and GPU blocks, pumps etc. (2xAIO).
 
If I went with the external radiator approach, I could always bolt both together and rather than using 3 fans each, use a duct and an 8 inch fan which should be much quieter than 6x120mms.

Making a duct like that would make hard work for my 3d printer, but I'm sure I can come up with something.
 
I was going to say, "Meh, nah, not DC!", but then I did some digging.

PWM fans are best because they can spin slower without stalling. However as discussed nobody seems to advertise if their PWM fan will stop.

However, the fans I want to stop don't need to run slow. They can almost be digital. I'd happily set them to 0-80-100 stepped curve.

That opens up a lot more options and DC fans are much cheaper.
 
Have you checked out Aquacomputer controllers? If memory serves at 0% PWM and/or below certain temperatuure they stop fans.
 
So getting everything setup and tested, what I have ended up with is:

The CPU rad fans won't stop, I haven't tested if this is an artefact of the fans or just the 40% minimum limit on the CPU headers. However they are low rpm PWM NZXT radiator fans. At 40% PWM they only spin at 400rpm and are silent.

The GPU radiator fans will stop at 0% PWM thankfully.

The CPU Pump is silent, barely audible at 100% and not audible at 80%. It doesn't stop, but again that might be the CPU header 40% limit.

The GPU pump, will stop. The unchangable LED on it glows brighter the higher the pump setting and goes off entirely if you stop the pump.

The single Fractal case fan at the back exhaust is DC with a 40% minimum, but can be stopped obviously.

I have tested it on passive only and ... I think it's going to overheat the GPU loop before it throttles the 3080. It made the radiator too hot to touch and I chickened out. I did find that 25% PWM on the GPU radiator fans and 100% on the pump the GPU will hold about 61*C running Furmark. Almost silent.

The CPU is another story. The cooling system loses 50*C before it even gets to the water. Trying to overheat it with prime95 I could get the CPU to 95*C before it throttled and the radiator was barely 40*C. I can try better thermal paste than the default NZXT stuff, but I'm not going to delid or lap it.
 
You need to have the pumps moving…. I had an old water block leak because the plate got too hot when I didn’t plug in the pump… you must have the water moving no matter what.

how are you talking the radiator temps ?
 
Was taking radiator temps with my fingers LOL. 40*C is roughly the limit for prolonged comfortable touch. 45*C it becomes uncomfortable after a while, 50*C it gets uncomfortable quickly and 60*C it's uncomfortable immediately. Above 55-60*C you start to get burnt. You can test with with water if you want. It's not exact, but it's gives you a round +/- 5*C estimate.

I do now have 2 thermo couples for the rads to fit today.

So far, I'm still finding the ways of the 3080 and games. For example, playing FarCry6 with VSync on at 75Hz the GPU wasn't even 100% loaded, fans sitting at 25% RPM temp around 51*C.

In VR, DCS World, Syria, High settings, Apache heli, however unsurprisingly floored it to 38FPS. Not temp, not power, but voltage limited. I expect some tweakage there and maybe knocking off a special effect or two. Out at sea it's 90FPS (Rift VSync), even around the Supercarrier. Fans barely hit 30% and temps barely hit 55*C though.

Pumps. I have settled for now on OFF until the chip is 30*C, then 40% until it gets to 45*C when it goes up to 80% and 100% at 50*C (similarly on both GPU and CPU). The CPU pump does not stop (1000rpm min), nor it's fans (200rpm min). The GPU pump does stop, however, the GPU is above 30*C after about 5 minutes and so the pump stays on around 40% constant anyway. I am tempted to just simplify this, find the audible point where I can notice the pump noise, back it down a bit and up that at the 50*C point to go to 100%. So just two levels, 90% of the time MEDIUM, and FULL when under load.

I haven't started overclocking anything yet either. I think I may try under voting the 3080 and see if that gives me any power and/or voltage limiter room for more clocks.
 
Another concern (2 actually) is the chipset temp and the motherboard temp. VRMs etc. are fine. It's a 200A board!

The chipset temp is a "known quantity" for the most part. It runs hot. They put a token fan no it on most MBs. Still runs hot. Not exactly best positioned under the GPU either. Gaming it doesn't hit more than 65*C, while others have seen 75*C and not had issues.

The "motherboard" temperature, as reported by the Asus Embedded Controller rises towards 50*C when the machine is passive. I profiled a rear exhaust fan to see if it was just stale air (even though there are 3x120mm rad fans doing 500rpm at idle). It has virtually no effect. I spun the 3x120 intake rad fans to 100% and slowly... over about 5 minutes the mother board temp came down to 35*C. Running the exhaust fan for now, keeps it around 45*C.

Less surprising then that my idle temps across the board are, 44, 43, 42, 43, 44. 500rpm 3x120mm intake rad. + 1x140 exhaust. Pumps 40%.

Maybe I need to lift the "idle cooling" to bring those under 40 across the board and see if it will settle without much noise... and return to those <40C temps after a bit of gaming... without too much noise.
 
Is intra-case cooling becoming a thing again? I have the option to move the Define 7 case into "storage" mode, as I don't have a reservoir which would allow me to mount a small nocuta behind it to circulate the air more cleanly over the board. (As a side effect it will also hide the GPU PCIe power birds nest and most of the water pipes.
 
Ah ha! I found how to tame the 5800X.

Undervolted the percision boost overdrive curves to -30mV and take the Max Boost Clock up to 5Ghz.

Gets me a "Rank 1" in single threaded benchmark in Cinebench and a Rank 4 for multi-threaded.
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