The most powerful fanless PSU aviable nowadays is the Enermax Digifanless 550 watts, with a peak power of up to 605 watts (one minute). Under this power envelope I fit:

- CPU: i7-4790K (90 watts)
- GPU: 2x EVGA GTX 980 SC ACX 2.0 in SLI (380 watts)
- MoBo: Asrock Z97M OC Formula (15 watts)
- RAM: G.Skill Trident X 32GBytes, DDR3-2400 (10 watts)
- SSD 1: Intel 750 PCI-E, 400 GB (25 watts)
- SSD 2: Samsung Evo 512 GB in M.2 format (5 watts)
- HDD 1: 3 TBytes WD Red (10 watts)

The HDD can turned on and off with a switch and will only used for back-ups. I'd love to get rid of a HDD, but it's silly to make back-ups on a SSD and it will be hardly ever turned on.

As you can see the maximal power draw is around 535 watts and very close to the limit of 550 watts. But in normal operation it's very unlikely to push all components at the same time. For peak power draw I have a buffer of 75 watts, what I can feel comfortable with.
Thankfully the PSU has a very high build quality (it it also very expensive, but never cheap out on the PSU) and I can measure the load and temperature in real time.
The measured peak load pulled from the PSU is about 510 watts.

Now I made sure the PSU don't blew up, I have to get rid of the heat somehow. The upper temperture limit for me is about 80°C with a max. room temperature of 30°C. As a result I have a temperature difference of 50°C to play with. So it's time for number crunching and it turned out I need three heat sinks of 400x300x84 mm, 12 kg each. So I designed the system around them.

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Yes, my friend, it is as exorbitant as it sounds!
My last build was highly focused on single thread performance and it works perfect for this workload.
However, I came across situations where I needed a considerable amount of compute power. As these workloads can be parallelized without a significant penalty, I developed a need for this number cruncher. Also I will use if for F@H during the night.
My first attempt was to use two E5-26xx v3 Xeons with the Z10PE-D8 WS motherboard. But it turned out to be way to expensive. Therefor I downgraded to two E5-2680 v1 Xeons on a Z9PE-D8 WS motherboard. As I saved a lot of money on the CPUs and the memory, I was able to include a Xeon Phi 31S1P. MATLAB is able to take advantage of the “automatic offload” feature to seamlessly integrate the Xeon Phi and boost the performance. I won’t write programs for the Phi by myself.
For the GPUs I will use one or two of the upcoming Polaris / Pascal line-up depending on the performance and price. I’m tending towards Polaris, but I have not enough information to decide.

This leads me to the part list:
CPU: 2x E5-2680 (8 cores, 2.7 GHz base clock, 3.5 GHz boost clock, 130 watts): used from Ebay
Coprocessor: Xeon Phi 31S1P (57 cores, 1.1 GHz, 8 GByte RAM, 270 watts): new from Ebay
RAM: 8x Hynix HMT31GR7CFR4C (8 GByte, DDR 3, 1600 MHz, ECC): used from Ebay
Motherboard: Asus Z9PE-D8 WS: new from retail (no used once available)
PSU: Corsair RM1000i: new from retail (I don't dare to use a used PSU)
GPU: 1-2x Polaris / Pascal (200 – 500 watts)
SSD 1: Samsung 850 Evo 1TB: salvaged from my first build
SSD 2: Intel 750: salvaged from my second build
WLAN: TP-Link Archer T9E: new from retail

As you probably know, I have an addiction to passive cooling. This time around I tried to get rid of the heat pipes. They are expensive and vulnerable. Also I'm lacking the appropriate tools to make a CPU block out of copper. Mounting the GPUs directly to the heat sinks proved itself as a good solution. Sadly, this is not feasible for the CPUs.
So I will use two Noctua NH-U12DX i4 cooler. But now I have to get rid of the fan somehow. This is certainly possible if you look at the definition of fan:

B1: an electric device with blades that turn quickly, used to move the air around.
B2: an object made of folded paper or other material that you wave with your hand in order to move the air around

So be filling the box up with mineral oil, I’m not only getting rid of the noise. There are no fans left in the build by applying this definition ;)
However, the build is not completely passive cooled, as the cooling used needs about 3 watts. But considering the total power this is negligible. So I will call it passive cooling. Also the oil itself is passive cooled.

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This project is a mixture of feasibility study, private study of thermodynamics, need for a new workstation / gaming rig and a…. insanity ;)

I study electrical engineering and I’m finished with my study next summer. I do a lot of work at home and game from time to time. Around last august I get annoyed by waiting up to 20 minutes to synthesizes a FGPA based design. And because I’m working next to my computer I wanted a very silent one. So I bought a “special silent system” from a (at least it looked like) distributor with a lot of good reviews…. It was a disaster. The sound was OK, but the CPU was hitting 97°C while rendering within minutes despite of the huge cooler. Luckily I could annul and get all my money back. So I decided to get a totally passive computer without a single moving part.

Because compiling requires a lot of memory bandwidth and single thread performance I’d like to use an i7 4790k (~90W). I don’t overclock the CPU but the “k” model offers better thermal performance.
Well when you google for powerful passive computers everybody says it’s impossible and/or insane. But since I have a calculator and a working brain the required 0.5 K/W are possible. With a heat sink around 10 kg ;)

The graphic card was and other story. Luckily Nvidia released the power efficient series just in time so I went with a GTX 970 Strix (~160W).

The rest of the components where:
MB: Asrock Z97M OC Formula
RAM: HyperX Beast, 2x, 8GB, DDR3-2133
PSU: Seasonic Platinum-520 Fanless
SSD1: Samsung 850 Pro, 256 GB
SSD2: Samsung 850 EVO, 1000 GB

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