Silent power, a designed from scratch computer cooled with cooper foam - Page 1
Forum section: electronics / general

author: senso
author_rank: Frequent Contributor
timestamp: August 03, 2014, 02:59:31 pm
content: So what are your toughs about the newest crazy crowd funding campaign?http://hackaday.com/2014/08/03/behold-the-most-insane-crowdfunding-campaign-ever/#comments

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 03, 2014, 03:24:38 pm
content: Copper foam smells like bullshit to me.High surface area, yes, but poor conductivity to all but the bottom layer, and probably poor natural airflowAnd it will look shit once it starts to oxidise

author: AndyC_772
author_rank: Super Contributor
timestamp: August 03, 2014, 03:26:48 pm
content: Copper foam? Really? Take a material with good thermal conductivity, but then replace 90% of the volume with trapped, still air in order to turn it into a good insulator...?

author: rob77
author_rank: Super Contributor
timestamp: August 03, 2014, 03:38:05 pm
content: that's bullshit - any foam is an excellent heat insulator because of the trapped air.if i would design a silent heat-sink, then i would rather investigate a possibility of using a honeycomb structure with vertical hexagonal pipes with open ends to allow convection take the heat away (in fact a shitload of small diameter hexagonal copper chimneys packed together)

author: Marco
author_rank: Super Contributor
timestamp: August 03, 2014, 03:49:18 pm
content: Copper isn't really that good a thermal conductor to begin with ... if you need transport more than a few cm you use heatpipes.

author: rob77
author_rank: Super Contributor
timestamp: August 03, 2014, 03:59:08 pm
content: Quote from: Marco on August 03, 2014, 03:49:18 pmyes, for sure - heat-pipes made of coppercopper is a good heat conductor, but it's not as good as black anodized aluminium when talking about heat radiation/dissipation.

author: rs20
author_rank: Super Contributor
timestamp: August 03, 2014, 04:04:05 pm
content: Quote from: rob77 on August 03, 2014, 03:38:05 pmOnly closed-cell foams trap air -- this is very much an open-cell foam, a coarse one at that, and it looks like the airflow (and therefore convection and potential heat transport) through that particular foam would be pretty free-flowing.The remaining question is whether the thin strands of copper leading from the bottom to the top will conduct well enough. Mental exercise -- imagine placing the heat sink in a super table vice and crushing it into solid copper. What would you be left with, a block of copper maybe a centimeter thick? The heat conductivity through that solid block is clearly going to be very good (A 2 inch x 1 cm cross-section block with 1 inch height works out to 0.13 K/W). But here's the kicker -- it seems like the average copper path length from bottom to top is maybe 50%-100% longer in the foam than the direct line possible in a solid block, so the thermal conductivity is only going to be 33%-50% worse. Let's say 0.26 K/W. Except it's radiating the whole way. Hardly a massive penalty for the foam factor. 100W works out to 26 degrees C over ambient in the copper alone (so yes, neglecting the actual radiation/conduction into air), which is pretty lax, but vaguely workable.Will this foam radiate heat as well as an traditional heatsink with the same volume of copper? Probably not. But might it be an acceptable compromise of interestingness/aesthetics vs performance? Pretty shaky, probably not. But it's certainly not as intrinsically absurd or off by orders of magnitude as many here are making it out to be. If it helps, think numerically about how electrically conductive the foam would be (to clear your mind of the "omg it's foam and there's air everywhere run away" preconception), and then refer those results back to the thermal world.Edit: Just to be clear that I basically agree that this isn't a good idea (with reservations), I offer another disadvantage: this foam would be a massive pain to clean dust from...

author: wraper
author_rank: Unknown
timestamp: August 03, 2014, 04:15:52 pm
content: Quote from: rob77 on August 03, 2014, 03:59:08 pmWhat funny about copper? Heatpipes are filled with water which circulates inside. Therefore heat is transferred through copper to very short distance. Black surface do not give any advantage when cooling is active. Strange how you compare heat conductivity vs radiation. Apples vs oranges.

author: rob77
author_rank: Super Contributor
timestamp: August 03, 2014, 04:23:46 pm
content: Quote from: wraper on August 03, 2014, 04:15:52 pmi'm not comparing conductivity vs radiaton - i was describing the copper - good heat conduction but not so good at radiation (because of it's color - and unfortunately copper can't be anodized to make it black)black surface will give you a relatively big advantage when talking about radiation without the aid of forced air circulation.so in fact i could say that you're comparing apples with orangesQuoteyou're comparing radiation with active cooling (forced airflow)

author: wraper
author_rank: Unknown
timestamp: August 03, 2014, 04:27:07 pm
content: Quote from: rs20 on August 03, 2014, 04:04:05 pmFunny maths. Path length maybe, but you forgot that the cross section of the copper became close to zero. Therefore calculate thermal conductivity for remaining copper cross section, but anything left for air.

author: wraper
author_rank: Unknown
timestamp: August 03, 2014, 04:30:18 pm
content: Quote from: rob77 on August 03, 2014, 04:23:46 pmHeatpipes = active cooling in 99% of cases. PC won't have passive cooling unless it is very low power.

author: rs20
author_rank: Super Contributor
timestamp: August 03, 2014, 04:36:06 pm
content: Quote from: wraper on August 03, 2014, 04:27:07 pmI didn't forget; the crushing the block in a vice part was accounting for that. Again, think about the electrical analogy. All those paths are in thermal parallel, so all that matters is the total cross section of the entire piece. If there's a decent density of copper in there, such that crushing it would bring it to 1 cm thick solid block, then that hypothetical solid block has the same thermal conductivity as the original foam, modulo the factor of 1.5 or 2 from the increased path length.Quote from: wraper on August 03, 2014, 04:15:52 pmWell put, worth just putting it in a table for clarity:Thermal Conductivity Emissivity (radiation)Aluminium Good (230 W/m/K) FairAnodized Aluminium Good (230 W/m/K) ExcellentCopper Excellent (380 W/m/K) GoodHeat pipe Hyper-excellent* N/A* Heat pipes don't really get much worse as they get longer (at least not as a simple reciprocal relationship), so a normal bulk thermal conductivity doesn't really make sense.One thing that's not clear to me -- radiation and conduction to air/convection are both relevant to heatsinks, I wonder what the breakdown is for the typical heatsink? Radiation must be some part of the story if manufacturers bother to anodize the heatsinks black, but if it was all about radiation, why does the fan need to move the air around? Is the heat radiated at wavelengths easily absorbed by air? I think thinking this through would be relevant to this discussion as well.

author: rob77
author_rank: Super Contributor
timestamp: August 03, 2014, 04:37:02 pm
content: Quote from: wraper on August 03, 2014, 04:30:18 pmare you even reading the posts you're replying to ?

author: wraper
author_rank: Unknown
timestamp: August 03, 2014, 04:50:22 pm
content: Quote from: rob77 on August 03, 2014, 04:37:02 pmReread 5 times your first post I quoted, It's my English got that wrong. So yeah, you did not compare conductivity/dissipation, talked as about separate things, sorry.QuoteExactly, the same as electrical conductivity. Now remove 95% of the copper volume from the wire and replace it with the air. Then measure electrical conductivity. Strange how all people on the earth did not find this way how to save copper in the wires by replacing it with foam.

author: rs20
author_rank: Super Contributor
timestamp: August 03, 2014, 05:10:55 pm
content: Quote from: wraper on August 03, 2014, 04:50:22 pmI've taken the volume drop into account in my calculations by reducing the width of the heatsink to 1cm (that's a foam density of around 10%, not orders of magnitude off) from its initial width of many inches; I got a result for the foam of 0.26 W/K.2.5 cm high, 5 cm deep, 10 cm wide, 10% density, 2.0 path length factor google link.Quote from: wraper on August 03, 2014, 04:50:22 pmIf you took the copper in a wire and fluffed it up so you had the SAME AMOUNT OF COPPER spread over a great cross section, then the conductivity would only be moderately worse. But that would obviously be an expensive and pointless operation since solid wire is rather easy to make and, say, twice as conductive as the foam. If the air around all those wires is actually needed for heat dissipation though, then it might just be a useful idea after all.

author: senso
author_rank: Frequent Contributor
timestamp: August 03, 2014, 05:19:14 pm
content: Even more striking for me is how 3 guys can get all the datasheets to implement a intel i7 processor, plus north-bridge, plus the graphics chip, don't you need to have access to the intel yellow and red books to create/design a motherboard?

author: rob77
author_rank: Super Contributor
timestamp: August 03, 2014, 05:21:47 pm
content: Quote from: senso on August 03, 2014, 05:19:14 pmprobably they're planning to buy an Intel NUC computer with i7 CPU and reverse engineer the schematics and then do the same with the graphics card

author: wraper
author_rank: Unknown
timestamp: August 03, 2014, 05:50:47 pm
content: Quote from: rs20 on August 03, 2014, 05:10:55 pmSo lets say that foam contains 10% of copper. Then you crush it to 10x smaller size and compare to solid copper block of the same size. Calculate 2X worse thermal conductivity. So you basically compare a foam with cross section 10x of the (very small) solid copper block, yet have 2x worse performance than it. When you expand that foam to previous size, you have 10x of the cross section with 2X worse thermal conductivity than that tiny solid copper block. Therefore 20 times worse per same cross section. Then we for example compare just some random regular copper heatsink with the same size as of that foam. 10% metal of the volume copper plates will have 2x better conductivity than foam. I don't get it. And yeah, regular copper heatsink plates are pretty thin, so using 10% copper foam actually might require more metal than copper plates of the same volume. Moreover so dense foam will be barely able to pass any air through it, so you will be forced to use much thinner foam for that reason, which again will make thermal conductivity much worse.

author: wraper
author_rank: Unknown
timestamp: August 03, 2014, 06:52:23 pm
content: BTW all those calculations are not precise anyway. Here I found some special foam with 8% copper of the volumehttp://www.ergaerospace.com/Copper-properties.htmThermal conductivity: 10.1 W/m-C = W/m*ksolid copper: 401 W/m*k.

author: Hole
author_rank: Contributor
timestamp: August 03, 2014, 07:12:29 pm
content: One thing to remember: if there is heat radiation there is absorption, too.Inside the foam all the radiation (good or bad due to color) is absorbed by its neighbors to a certain degree. So effectively only the outside surfaces of the foam do transport heat away by radiation.

author: rob77
author_rank: Super Contributor
timestamp: August 03, 2014, 07:23:08 pm
content: Quote from: wraper on August 03, 2014, 06:52:23 pmthanks for the link !i was wondering what the exact figure looks like... so it's more than clear that the copper foam is the worst heatsink ever considered in a computer design

author: wraper
author_rank: Unknown
timestamp: August 03, 2014, 08:22:43 pm
content: Looked at this stuff closely. It's not anything near the proper copper foam with a solid structure as in the link I gave. It more like freaking metal sponge.

author: dave_k
author_rank: Frequent Contributor
timestamp: August 03, 2014, 09:59:03 pm
content: I'm still waiting to find out what cooper foam is....

author: rs20
author_rank: Super Contributor
timestamp: August 04, 2014, 02:17:23 am
content: Quote from: wraper on August 03, 2014, 05:50:47 pmTo make it easy for you, I provided a calculation with the path length factor (2) and the volume factor (10) taken out, and got my figure of 0.26 K/W. Still you think you're telling me something new. Here it is again, please don't respond to me again without specifically criticizing this calculation:Quote from: rs20 on August 03, 2014, 05:10:55 pmQuote from: wraper on August 03, 2014, 06:52:23 pmFirstly, from that page you linked to, "Thermal Conductivity Copper has an extremelyhighthermal conductivity. Duocel® copper foam is used in very high performance heat exchangers where weight and cost are of low priority." So, let's plug that bulk number of 10.1 into my calculation:2.5 cm high, 5 cm deep, 10 cm wide, Duocel copper foam google link.Stop the presses! It works out to 0.5 K/W. Furthermore, plug the density you found on that page, and the "tortuosity factor" of 3 fromDuocel Foam Thermal Conductivity( I had guessed 2 ) into my first equation, and my original answerchanges to 0.49 K/W. Pretty much bang on. I find this thread in particular to be a strange one for being called "completely wrong" for being off by 50%.

author: wraper
author_rank: Unknown
timestamp: August 04, 2014, 08:33:43 am
content: Quote from: rs20 on August 04, 2014, 02:17:23 amDidn't tell you something new. Just wrote how I understand your calculations and compared that with regular heatsink.QuotePicked best possible foam, not some metal sponge as in that computer. What's wrong?QuoteBut again heat exchanger != regular heatsink. There are very high pressure inside which pushes medium through it. They make it up to size: Duocel® copper foam is limited to 1" x 6" x 18" . As heat will come from both sides of the foam in heat exchangers, longest distance heat will need to travel through the foam is 1.25cm. So suppose in the heat exchangers surface area is more important than thermal conductivity. And this foam is much more dense than you would be able to use with simple fan and especially free air flow. If you think that such thermal conductivity is enough, it's not so simple. Even in regular heatsinks with plates which have better thermal conducticity than that foam, heatpipes are used (talking about PC heatsinks where you need to dissipate a lot of heat in restricted volume, not thick ones used in amplifiers, etc.). Just because if heat need to travel through the plate more than few centimeters, it becomes a problem as plate is hot in one end and cool in another. Yet even heatsink with such plate density as PC ones (= high surface area) are not any good for free convection.

author: wraper
author_rank: Unknown
timestamp: August 04, 2014, 09:42:50 am
content: Talking about that particular computer implementation, not heatsink. Just noticed total bullshit. Do they intend to mount CPU and GPU on riser board, or some other mystical way above the main board where the RAM is located according to this picture.

author: TMM
author_rank: Frequent Contributor
timestamp: August 04, 2014, 09:54:51 am
content: A completely fanless desktop PC can be done.Zalman have produced a few fanless cases in the past, e.g. the Zalman TNN-500. They use heatpipes to transfer the heat from the main components to the case which is basically a giant aluminium heatsink.I doubt however that Zalmans cases from the past would be enough to cool a modern high end graphics card (e.g. GTX780). CPU's haven't really increased in thermal output so you could still run a top of the line CPU.Quote from: rs20 on August 03, 2014, 05:10:55 pmIt's actually a terrible idea because with all that surface area the 'wire' (foam) would corrode in no time flat when placed in a moist environment.

author: rob77
author_rank: Super Contributor
timestamp: August 04, 2014, 10:01:49 am
content: Quote from: wraper on August 04, 2014, 09:42:50 amof course it's bullshitthey can't route DDR3 signals easily between boards (probably not even possible). they would have to place the RAM chips to the same board as the CPU or GPU.i think it's just another SOAP like projectthe guys behind this "project" are too optimistic and they're suffering from lack of knowledge

author: rs20
author_rank: Super Contributor
timestamp: August 04, 2014, 12:34:18 pm
content: Quote from: wraper on August 04, 2014, 08:33:43 amWow, look at all those numbers backing up your statements. I'm sure the heatsink would work better if it had iced water pumping through it, but that's not what we're doing here, so why are you mentioning it? I don't care if magical diamonds exist that defy the laws of thermodynamics, we don't have that here, so it's not relevant. If you have numbers to back up your claim that the air would have trouble escaping the foam (and I do suspect you might be right there, although it looks like quite a open, coarse foam) then I'd be interested to see that. In any case, you were talking about the conductivity of the foam for ages, and now you've suddenly switched gear to the convection of the air. I've made you backpedal on the point that the conductivity of the foam itself is pretty close to good enough for the job, which is all I was ever claiming -- since everyone before in this thread just immediately deridedanyfoam as "an excellent insulator".BTW, stock Intel heatsinks have no heatpipes inside them, and they work well enough (yes, with a fan), so heatpipes aren't relevant either.Like I've said at the start, this is not an optimal design. But just because the design is bad doesn't make thinking it's bad for incorrect reasons (e.g. "copper foam is an excellent insulator") a good thing, or a thing not worth calling out.

author: wraper
author_rank: Unknown
timestamp: August 04, 2014, 02:54:35 pm
content: Quote from: rs20 on August 04, 2014, 12:34:18 pmBecause if you want to directly compare regular heatsink with that foam while using regular fan, you would need to make that foam much thinner so the fan can do it's job. Reason for air resistance is because there is no direct path through it, like in the simple heatsink.http://en.wikipedia.org/wiki/Drag_(physics)I never wanted to insult you BTW.

author: wraper
author_rank: Unknown
timestamp: August 04, 2014, 03:09:13 pm
content: http://www.silentpcreview.com/intel-i7-hsfIntel do heat pipes actually. Their stock coolers for high end CPU's suck, but for lower end are usually pretty adequate last years. Thou intel do the trick with massive copper core in the middle, so they are not completely simple heatsinks.

author: edavid
author_rank: Super Contributor
timestamp: August 04, 2014, 04:19:37 pm
content: Quote from: rob77 on August 04, 2014, 10:01:49 amI don't know about easily, but it's obvious that you can route DDR3 signals from a motherboard onto a DIMM. CPU board -> riser -> RAM board should work too if the traces aren't too long.

author: zapta
author_rank: Super Contributor
timestamp: August 04, 2014, 04:22:33 pm
content: Quote from: wraper on August 04, 2014, 03:09:13 pmGreat idea. It can function also as a solder tip cleaner.

author: rob77
author_rank: Super Contributor
timestamp: August 04, 2014, 04:26:52 pm
content: Quote from: edavid on August 04, 2014, 04:19:37 pmactually i haven't seen DDR3 modules on a riser boardit was common back in the times of slower RAMs, but haven't seen anything like that nowadays... especially when the RAM controllers are integrated in the CPU.and not talking about the GPU's RAM - that's usually even faster (and even more "touchy" in terms of signal integrity).EDIT: of course i mean DDR3 DIMM modules on a riser board.

author: AndyC_772
author_rank: Super Contributor
timestamp: August 04, 2014, 04:35:12 pm
content: It might be just about OK if only one bank of DDR3 is to be supported. Against all odds, DIMMs work OK even with multiple DIMMs connected to each line, so the extra trace length and impedance discontinuity might be acceptable in a simpler system. The only way to be sure is to spend some time with a proper SI simulation package and an engineer who knows how to use an IBIS model properly.

author: mzzj
author_rank: Super Contributor
timestamp: August 06, 2014, 01:43:15 pm
content: Quote from: rs20 on August 03, 2014, 04:36:06 pmRadiation effects are something like 5 to 40% of total heatflow depending on your case.For example 50 mm piece of Fischer SK174 heatsink @ 300K ambient temperature(air and radiation temperature) with 60K temperature rise:specified thermal resistance ~6K/wwith a 60K temperature rise that works out to 12 watts or so.Stefan-Bolzmann law gives us ~4,5W of radiation cooling assuming perfect 1.0 emissivity and 94cm2 outer surface area for the heat sink.Radiation cooling has lesser effect on finned structures and with forced air cooling it has generally minimal net effect.Under cloudless night sky the radiation cooling effect can account 100% of the cooling when heatsink temperature drops below ambient air temperature!

author: rs20
author_rank: Super Contributor
timestamp: August 07, 2014, 07:12:45 am
content: Quote from: mzzj on August 06, 2014, 01:43:15 pmInteresting, thanks. Shows how insignificant emission is in many cases. It's worth noting that a finned heatsink may have a large surface area, but most of the emitted radiation will be re-absorbed by another fin of the heatsink! Perhaps you took this into account with your "outer surface area" (not sure if you were looking at the surfaces that are only facing free space). The other thing is that any surface is always absorbing radiant heat as well as emitting it, the Stefan-Bolzmann law only gives you one half of that equilibrium. For example, applying the Stefan-Bolzmann law to the human body gives an emission rate of 550W -- which would be rapidly lethal rate of temperature loss, except everything around is is at at least 273 kelvin as well so we're bathed in almost 550W of incoming radiant heat as well. So the net emission of our heatsink is ~4.5Wminus incoming radiation. Again, I'm just clarifying, you did touch on this with your cloudless night sky comment.

author: mzzj
author_rank: Super Contributor
timestamp: August 08, 2014, 10:10:53 am
content: Quote from: rs20 on August 07, 2014, 07:12:45 amyeah, calculated the surface area based on outer dimensions exactly for the reasons you said.And yes, i did take incoming radiation also in consideration. (Thats why i mention 300K ambient radiation temperature.)

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 08, 2014, 10:25:07 am
content: Also, since radiation has a Tabs^4 dependence, you get vastly more thermal conductivity at elevated temperatures. That is, if you want a lower thermal resistance due to radiation, you MUST run it HOT!Vacuum is a rather awful conductor, which gives some clues about the design of vacuum tubes (back in the day). The cathode in the center is hot, closely positioned near the grid, which must remain cool (otherwise it goes leaky). The grid is usually molybdenum wire wound on copper supports, with radiator flags tacked on the top. So the grid can stay somewhat near outer glass temperatures, being heatsunk by those flags. The anode surrounds everything, and gets hot (it's where all the electrical power is going!), sometimes awfully hot (transmitter tubes made with graphite or tantalum anodes are intended to run red-hot!), hotter than the grid should be. And around everything, there's a glass envelope, which typically runs over 200C at the hottest point -- so anything inside the vacuum is running nearly double room temperature (absolute scale), which helps greatly with radiation -- as long as the baseline temperatures are tolerable!In vacuum lab equipment, you have to use non-outgassing PCBs (RF teflon stuff, Rogers whatever -- FR4 is no good), which conduct more poorly to begin with. Thin copper traces don't account for much, so you can very easily have a jellybean op-amp dissipating not 100mW, yet burning up because there's no short path out! Often, a huge copper braid is used, not so much for grounding as heatsinking: over such length, even though it's copper, the thermal resistance sucks, but vacuum sucks more (ha..), so it's a net win.Lessons not all that applicable to consumery stuff (< 150C silicon, enough watts that you need a fan), but good to keep in mind all the same.Tim

author: tszaboo
author_rank: Super Contributor
timestamp: August 08, 2014, 12:04:08 pm
content: You actually have problem with the copper foam?I7: 300 USDGTX760: 250 USD500GB SSD: 300 USD8GB memory: 100 USDPut it together, and it becomes 930 USD, what they are asking for. Without power supply, motherboard copper foil, case, and most important, the design.

author: macgyver0815
author_rank: Contributor
timestamp: August 09, 2014, 02:47:33 pm
content: Quote from: NANDBlog on August 08, 2014, 12:04:08 pmWell these are consumer prices. First, if you buy these as a reseller you get volume discounts (the reseller has to make money from selling you stuff, often the resellers earn way more than the manufacturers).Second, if you buy the components in >100pcs quantities and manufacture the cards yourself you can get it even cheaper (the manufacturer of the normal retail cards also have to make money from something).Then these guys sell it directly, without resellers in between.But I still expect very low margin as their production volume is not *that* high.Oh and it is of course possible to put the DDR3 memory on a second PCB through a high speed connector. Not the best idea IMHO, but it can work (I have done DDR3 PCB layouts, so I know a bit about this stuff).Also creating such a complex board with a small team is not impossible (several small industrial embedded PC vendors proof that). Very hard work, very hard to get right the first time, but very possible if you spent enough time.The cost that the large manufacturers have here is paying several good engineers (say 100k$/a each) over several month fulltime work. This cost is 0 if you work for free.That copper "foam" is actually a quite interesting material. But I also do not think that it will work @>100W without good airflow. I see the thermal design as the major technical issue of this project - the rest is not unrealistic (though I don't know if they actually have enough experience to do it properly...).

author: Fsck
author_rank: Super Contributor
timestamp: August 10, 2014, 12:10:26 am
content: you can find ddr3 on risers in high density multisocket servers, it's just annoying to do. also as macgyver0815 pointed out, not the easiest thing in the world. also if the nvm and ram are on the same board, you're probably going to be in a world of hurt when it comes to QC...

author: rob77
author_rank: Super Contributor
timestamp: August 10, 2014, 08:55:18 am
content: Quote from: Fsck on August 10, 2014, 12:10:26 amactually i work with high density servers (HP blade servers) and all the DIMM sockets are packed as close to the CPU sockets as possible on the main board (and we have machines with half a terabyte of ram).

author: corrado33
author_rank: Frequent Contributor
timestamp: August 11, 2014, 04:42:28 am
content: Don't quite know if this was mentioned, but a heatsink needs proper contact with the hot device in order to drain the heat away.I doubt this foam is making proper contact.I mean hell, I've had computers overheat before because the heatsink wasn't connecting on a freaking corner, with 3/4 or it connecting just fine...

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 11, 2014, 07:22:22 am
content: Presumably there's a base plate it's soldered or brazed to...With forced air cooling, and some solid fins to bring heat up into the center of the foam, it wouldn't be too bad. But you're probably better off with the regular array of fins construction at that point, so who cares?Tim

author: Fsck
author_rank: Super Contributor
timestamp: August 11, 2014, 03:27:30 pm
content: Quote from: rob77 on August 10, 2014, 08:55:18 amsorry, I type before I think too often. forgot that blades even exist as they're usually low memory, but are definitely the highest density.was thinking high end multisocket systems. the linked board will take 6TB of memory on risers over 4 sockets. the 2010-era nehalem-ex 8-sockets would take 1TB.http://www.supermicro.com/products/motherboard/Xeon/C600/X10QBI.cfm

author: rob77
author_rank: Super Contributor
timestamp: August 11, 2014, 09:45:57 pm
content: Quote from: Fsck on August 11, 2014, 03:27:30 pmbut it looks like there is some kind of buffer/controller on those memory boards (the 2 heatsinks between the connector and the actual DIMM slots).. so it's not just routing the DDR3 signals to a different board.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 11, 2014, 10:16:43 pm
content: Hmm, hard to say. They'll definitely want VREF drivers on the daughterboards, but they may well have more chips than that alone. Wish the pictures had zoom.I don't know what the fanout of SSTL_15 looks like, can't imagine it's too pretty after a hundred though. Drivers per card array seem more likely than direct connecting everything.Tim

author: Fsck
author_rank: Super Contributor
timestamp: August 11, 2014, 11:03:56 pm
content: Quote from: rob77 on August 11, 2014, 09:45:57 pmcorrect. aka: annoying to do.