- FINISHED- Full passive powerful workstation / gaming rig... who said it can't be done?

[Stefan1024]

According to your voting this build is officially named: "Silence! I kill you!"

 

 

 

Part 1

 

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. But I only find one single heavily overpriced distributor.

 

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

... and a DVD drive (OK this is the only moving part in the PC but I'm using it around once a month)

 

As far I knew the key components I was looking for the heat sinks. New once are very expensive, but I got four used heat sinks (20 kg at all) for 150 Euro. The next step was to construct the rest of the system around the heat sinks in Solidworks.

 

 

 

Part 2 follow soon....

And don't forget to vote. I need a name for the build.

[MeltingPoint]

Interesting project.

 

Why don't you incorporate the CPU cooling into the massive heatsinks?

[christianled59]

Woah amazing. Followed.

[KaminKevCrew]

Very cool looking project you have there, definitely keeping an eye on this!

[ManWithBeard1990]

I'd like to suggest a couple of things

 

The basics of your project are good and the GPU will probably have enough cooling with this setup, but I'm not convinced the CPU will. The Megahalems (I think that's what it is) is a capable heatsink but mounting it the way you did will not aid convection very much because the air doesn't flow upwards through it. It'll stay okay until the whole thing is soaked with heat and then it'll throttle. I'd suggest something like a Noctua NH-C14 instead, with perhaps a chimney on top to extract the air using the stack effect. Mind you, for this to work the chimney needs to be reasonably tall.

[Stefan1024]

Thanks for all you tips. The CPU is also connected to the big heat sink.

 

The project is more or less finished and the cooling works well. Just give me some minutes to write the next parts

[EpicallyEvil]

Im looking forward to seeing the finished project!

[Stefan1024]

Part 2: Drilling, soldering, screwing…

 

The next part was getting all electrical parts as well as the metal sheets, the heat pipes and the copper blocks.

 

For the CPU I used four self-bent 6mm heat pipes. To be honest it is a pain in the ass to do it properly. As a result I managed to get four custom bent 8mm heat pipes for the GPU. The HPs are then sandwiched between two copper blocks which makes the contact to the CPU / GPU and the heat sink. For the CPU I also used a Prolimatech Megahalems to get the precision mounting hardware, because I don’t have access to a milling machine. And mismatching mechanical parts put a lot of stress to the PCB.

 

Well the whole metal work was one of the main reasons for this DIY project. I can’t sit three years in school without doing something with my hands from time to time. ^^

 

For the motherboard tray I simply cut an old case apart. Also a consequence of a missing milling machine. It is not very well looking but it does the job good enough.

 

A few more words about the cooling. The thermal conductivity from the core to the heat sink is extremely important. There are so many transitions: CPU -> IHS -> Copper block -> HP -> Copper block -> aluminium heat sink

When you reach 0.05 K/W per transition (what is already a very good value) already the half of the overall 0.5 K/W is used.

 

While this can be calculated somehow, other values can only be estimated. Does anybody know how much heat in watt is produced by the VRM of the graphic card? Or the coils, VRAM….

 

My first attempt was to use the fanciest heat sink that fits in two PCI slots:

 

Stock VRM heat sink (black) vs. new one

 

You guessed it: It’s not sufficient! I got once the chance to borrow a thermal image camera. And with ~100°C I don’t feel comfortable. Even thought for a short period the temperatures are fine, the electrolyte capacitors next to it can only handle around 80°C.

 

Here are some more thermal images:

 

 

 

 

 

 

In the next part I show how to lower the VRM / coil temperature and add some AIDA64 results.

[Stefan1024]

Pics:

[Stefan1024]

Part 3: GPU cooling, closer look

 

Welcome to Part 3 where we will have a closer look on the GPU cooling. For some tests I added another GTX 970 Strix in SLI for comparison. The room temperature during test was around 23°C.

 

 

The GPU itself and the VRAM are connected to the two heat sinks in the front, what works fine. The heat capacity of the massive aluminium heat sinks is so big, the GPU needs 30 minutes of Furmark to hit around 71 °C. Look how fast the original Strix is heating up. Even after long gaming sessions I never get over 74°C.  The copper block on the GPU peaks around 53 °C. So the VRAM stays cool to. Unlike on the Titan X with >90°C!

 

 

The VRM is actually the hottest part on the card. We already discovered that in the second part. Aida64 reported up to 104°C. Not a core meltdown, but definitely reduced lifespan. So I ordered a VRMR2 from Termalright. By the way, it a shame they don’t produce cooler like this anymore. Luckily they had one in stock in France. After cutting the cooler into shape I glued it to the coils with Arctic Silver thermal adhesive. Because it’s only contacting the top of the coil, the capacity of the glue is no problem.

 

This action also reduced the coil whine, which feels extremely loud when no other noise source is in your computer. But it is still noticeable and annoying. Within the next few days I will get some sound absorption foam to get rid of it.

 

The VRM now peaks 97°C. This is only 2°C more than the original cooler. The VRMR2 takes the heat away from the coils fast, but is not so good to dissipate the heat to the air. Maybe in summer when it’s 35°C I may add a small, slow spinning fan. I really recommend integrating the VRM cooling to the main cooling. But without a milling machine it’s a pain in the ass. A backside cooler from arctic cooling might also work, but I can’t remove the back plait anymore since the screws are blocked. Well it won’t fit anyway

 

After all I have to say the GTX 970 is still a good, 3.5 GB VRAM card. Dragon age inquisition on 2560x1600 with max setting but without MSAA runs fluent.

Because of the RAM story and the leak of documentation for the TK1 (I’m using in another project) I don’t like Nvidia much anymore. But for a project like this you have no choice.  But please don’t talk about the “VRAM gate” in this post OK?^^

 

Since a have no more access to a 6000 Euro thermal image camera anymore I can only show you the AIDA64 results, sorry.

 

The next part will be about the CPU cooling. Do you like more or less details in the further parts?

[123h54ah56Sfdg54wh]

Really enjoyed reading through your posts, looks like you've got a clear goal in mind and know how to get there! Will definitely keep reading this. I have one question though, I was wondering how you've connected the 20kg heatsinks that you bought to the components. I can't seem to figure it out by the pictures myself.  

[Stefan1024]

Really enjoyed reading through your posts, looks like you've got a clear goal in mind and know how to get there! Will definitely keep reading this. I have one question though, I was wondering how you've connected the 20kg heatsinks that you bought to the components. I can't seem to figure it out by the pictures myself.  

 

Thanks

 

I bent / let bent some heat pipes. The ends of the pipes I press between two copper half shell. One copper block is connected to the heat source and the other one is between the two heatsinks.

[WoodenMarker]

Gosh, this is great. (It's not the prettiest thing though.)

[0ld_Chicken]

Very nice. I really had no interest in quiet a pc until recently. This is the most original idea I've come across yet! Can't wait to see more

[ELSknutson]

Looks like a makeshift boat anchor. I bet that thing weighs 50+ lbs

[christianled59]

Looks like a makeshift boat anchor. I bet that thing weighs 50+ lbs

But it's quiet. :D :D

[Stefan1024]

Part 4: Cooling the CPU and what can go wrong when you have no room for errors

 

So I this part I will cover the CPU cooling and discuss the difference between heat capacity and heat dissipation.

 

I made the CPU cooling before the GPU cooling. Actually it was the first thing I did after cutting the motherboard tray out of the old case. And since I’m not a professional mechanic (I only made a three month course 6 years ago) my skill was a bit… rusty. Therefor the holes in the copper blocks get around 0.4 mm to big because the drill was eccentric. Because I wasted some copper before on an error I hadn’t anymore copper left to do it again so I went with it.

 

 

This caused some bad thermal contact between the copper half shells and the heat pipes. As a result the CPU thermal throttles in Prime95. But the program is cruel anyway. The i7 4790k is rated at 84/88 watts. During Prime it consumes 120 watts and more. Not the power the cooling was designed for! I added a buffer of 50% by design, but this is used up by the mechanic. So I had to limit the CPU power in the bios to 90 watts (100 watts for short time limit). Now the CPU stays under 90°C when the heat sink it hot (> 1 hour of full load) and around 80°C during the first 15 minutes as long as the heat capacity of the heat sinks offers some extra cooling. The impact of the power limitation in Cinebench is around 3% (score of 817 instead of 841).

 

The cooling performance is limited by the heat transfer. While the CPU is hotter than the GPU, the CPU heat sink is cooler than the GPU one.

 

Intel recommends a maximum temperature of the IHS of 74°C and in full load I’m a bit over this. But unless the GPU which is stressed 100% all the time during gaming, the CPU has around 40% load in Dragon Age Inquisition (what is a CPU demanding game).

While working the CPU is only utilized 100% during compilation, what only takes up 10 minutes. Afterwards the heat sink can cool down again. Therefore to core temperature of the hottest core stays under 85°C during 98% of the time. Only while rendering in Solidworks it goes above 85°C, but I do this seldom. The idle temperature (Internet, word…) is around 35 – 40°C.

 

Consider the 5k iMac, where the i7 4790k hits 100°C within one minute! I’m not concerned about the lifespan of my CPU at all. Linus made a good (has he ever made a bad one?^^) video about it:

https://www.youtube.com/watch?v=tgTMxB-ffjM&list=PL8mG-RkN2uTxk-i5le7KJUx-zLmDuBiWD&index=1 (starting at 2:30)

 

So here we are. Depending on your workload you can use the heat capacity to reduce the heat sink size or getting a small room for errors.

But I recommend to plan a big margin >= 50% for your design. The system will be massive and heavy anyway. If you are interested in a fanless media PC (< 50W) get something like a C3LH-B from Impactics.

The system I made has a TDP of > 250 W. Don’t expect you can take it with you to the next LAN party.

 

I don’t know the actual weight but it is over 30 kg for sure. I needed the help of my girlfriend to move it into position. All metal sheets are made of 1.5 mm thick stainless steel. And it bends over 1 cm while lifting. This really hurts in the eyes to look at it

 

Is it bulky? Yes.

Is it expensive? Yes.

Is it time consuming? Yes.

Is it insane? For sure^^

Do I like it? Hell yeah!

 

Ok what’s left? The coil whine is still noticeable. I should receive the sound dampening foam by the end to the week so I can deal with it. Then you will also get some more pics of the finished system.

 

Although I already added a lot of my personal experiences and advises to this thread, is anybody interested in a “how to design a passive cooled system” guide?

 

Stay tuned for the next part. Meanwhile you may can give me a hand with my audio problem:

http://linustechtips.com/main/topic/339559-exchange-swap-stereo-channels-on-spdif-toslink-by-software/

 

I don’t mid to spend a few bucks on hardware or software to solve it.

 

[Ceatra]

noice

[ManWithBeard1990]

Impressive. I hadn't considered the CPU being heatpiped to the big-ass heatsink too. Where do you buy heatpipes anyway?

[spwath]

Wow that's cool.

Also, uh... What is that last pic?

What is "mental cinema"

[thatguy321]

Also, uh... What is that last pic?

If you don't know, we can't tell you...

 

Awesome build!!

[spwath]

If you don't know, we can't tell you...

 

Awesome build!!

OK, its what i thought then

[cesrai]

Don't use kompuster it's a card killer.

 

Nice build tho and dafuq stay on topic man and thermal image of a topless images isn't related what so ever to this build log.

[Stefan1024]

Impressive. I hadn't considered the CPU being heatpiped to the big-ass heatsink too. Where do you buy heatpipes anyway?

 

CPU:

HP 6mm x 300 mm from Impactics, bought at https://www.caseking.de/shop/catalog/Silent-PC/Fanless-Systeme/Impactics-Heatpipe-2er-Set-6x300-mm::16958.html

~ 8 Euro per piece

 

GPU

HP 8 mm x 450 mm from SITUS technical, bought at http://www.situs-tec.de/

~ 40 Euro per piece including the three custom bends per HP

 

I was searching a long time where to buy them. It look like there in no cheap source and you can't get around them....

[Stefan1024]

Part 5: Even a fanless system isn’t noiseless

 

Even though the fluid in the heat pipes is the only moving object in the system by design, the PC isn’t completely noiseless. Like mentioned in the previous parts the coils vibrate under heavy load and produce this very annoying sound. According to the spectrum analyser on my smartphone it is a 5 kHz tone.

 

I already stabilized the housing of the coils on the GPU with the heat sink, and it doesn’t get better by holding it tight to suppress vibration -> it’s not the GPU (anymore)

The next usual suspect after the GPU is the PSU. So I mould all coils I could find in the PSU with hot glue. The thermal image have shown it doesn’t get to hot and the glue can withstand 110°C. But I looks like Seasonic already did quite a good job considering it’s a mass production.

 

Ok put the PSU back in, start up, fire Unigine valley, expect pure silence and hear…. The same noise again. Although I thought it’s a bit quieter, but that’s hard to tell on such low volumes without direct comparison.

With heavy load on the GPU only the system is now almost silence. But the VRM on the motherboard still produces a buzzing, but on lower pitch than the common coil whine. And I discovered all remaining high pitched whine comes from my phone charger.

 

To modify the Mobo I have to demount it. It’s a Z97M OC Formula from Asrock. Due to the construction of the PC this is the worst case, because it requires removing all the big heat sinks. I’m not in the mood to do it. And I can’t blame Asrock. The buzzing is quiet and in every normal setup the fans will overpower it. So I added some non-flammable acoustic dampening material (ME50SK PYRAMID from SWILO). This material is great and cheap.

 

Because of the logarithmic behaviour of the human ear, I can still hear it. But only when I mute the speakers while gaming, turn of the printer (man this thing is load in standby!), wait until no car is driving by and listen carefully. Then I could hear something around the auditory threshold. Not an everyday situation

 

So I’m finished with the hardware now! And I proofed fully passive cooled system with a TDP of >250 watts is possible! Heavy overclocking is not possible, because it was never designed to be. And the performance gain compared to the power consumption is just ridiculous.

 

Sorry Linus this build won’t fit in your cabinet, but it will be quieter! 

 

I will make another part with all the cost and distributors. And a comparison to other solutions. But you are very welcome to comment by build. By the way it’s the first I made. I haven’t even swapped a CPU cooler before!