The Not-So-Cool Future

markmcb writes "Researchers at Purdue University and several other universities are looking to start work on a major problem standing in the way of future chip design: heat. The team is proposing a new center to consolidate efforts in finding solutions for the problem that is expected to become a reality within the next 15 years as future chips are expected to produce around 10 times as much heat as today's chips. The new center would work to develop circuits that consume less electricity and couple them with micro cooling devices."

Comments

But think about the,,,

[Deltaspectre]

Think about the people up in northern Canada, who need that precious heat! Unless this is some evil conspiracy to kill them off?

Nothing new

[koreaman]

What this boils down to is "researches are looking at ways to make cooler chips." Well, duh, haven't they always?

Re:Nothing new

[lrichardson]

A few years back, I read a couple of articles about reversible chips ... run the op through one way, store the results, then run the exact mirror back through. Net heat result was (theoretically) zero. Reality was about 1-2% of regular heat build-up. But I haven't heard anything more on this. Sure, it effectively halves chip speed. And, even at the time, I thought it would be insane to engineer with the pre-emptive tasking coming into vogue. But something that drops heat production by two orders of magnitude seemed worthwhile pursuing. Anyone else heard where this research is at?

Re:Nothing new

[eliasen]

Why is the parent moderated funny?

Reversible computation is quite real, but it doesn't work in the way you explained. You don't need to actually run the computation backwards. To make a long story short, the only time that a reversible computer needs to expend energy as heat is when it's producing output, or setting/clearing variables to a known state. And then, it only requires energy proportional to the number of bits being output, and the temperature. So if you're testing whether a billion-digit number is prime, the entire calculation can take zero energy, except for the one bit of output.

Unfortunately, to get truly reversible computing, the computation has to be done arbitrarily slowly.

If you don't have it, Feynman Lectures on Computation has one of the clearest discussions of reversible computation. Very highly recommended, and fun. We're 35+ years past the time when Feynman made these lectures, and we're still nowhere close to the limits or the technology that he described. Techniques for varying the power supply on the chip alone would very greatly reduce energy usage.

Photonic chips?

[Mysticalfruit]

I thought the future of processors was going ot be photonic processors. I'm not sure if these will be producing any heat or not.

Re:Photonic chips?

[Rorschach1]

Thermodynamics makes sure of that.

Minimum Energy Requirements of Information Transfer and Computing

Not Cooling

[LordoftheFrings]

I think that the solution to the heat problem will not come with better and more powerful cooling solutions, but rather radically changing how chips are designed and manufactured. The article doesn't contradict this, but I just want to emphasize that. Having some liquid nitrogen cooling unit is not the optimal, or even a good solution.

diamond cooling

[myukew]

they should look for ways to mass produce cheap diamonds.
Diamonds are about five times better at heat conducting as copper and could thus be used for passive cooling.

Re:diamond cooling

[kebes]

Actually many researchers are in fact seriously pursuing using diamond as a future replacement for silicon. Both diamond and silicon are *very bad* conductors in their pure state. Both have to be doped (with phosphorous, boron, etc.) to become p-type or n-type semiconductors, which makes them useful as a substrate for microprocessors (note that when doped they are semiconductors, not conductors... your microchip would just short-out if the entire wafer was made of a metal/conductor).

Diamond's superior thermal, optical, and chemical-resistance properties make it attractive for future microprocessors... but unfortunately it is more difficult to make it work as a semiconductor, which is why silicon has always been the substrate of choice.

It's very interesting research, and we'll see where it goes. For more info, this C&E News article is good, or check here, or here and there's a bit here.

1kW?!

[AaronLawrence]

("ten times as much heat as today's processors")
I don't think that 1kW processors will be practical. Nobody is going to want to pay to run that, and nobody will want a heater running in their room all the time either.

I'd say that they should be looking to limit it to not much more than current figures (100W) - maybe 200W if we are generous. After that it gets silly.

Re:1kW?!

[kebes]

FTA:
Current chips generate about 50-100 watts of heat per square centimeter.
"But in the future, say 15 to 20 years from now, the heat generation will likely be much more than that, especially in so-called hot spots, where several kilowatts of heat per square centimeter may be generated over very small regions of the chip..."

Let's not confuse power with power density. When the article says "10 times the heat" they mean kW/cm^2, not kW. Chips of the future will generate a few kW/cm^2 of heat in their hottest spots, but they will still be supplied from conventional 200W power supplies that run off of normal 120V power lines. It's the dissipation of so much heat in such a small area that is the issue, not the raw amount of energy being consumed.

So, again, it's not the the processor will draw 1 kW of power (it may draw considerably less), but rather that it's hottest spots will need to dissipate ~1 kW/cm^2 (i.e.: 1000 joules of heat per second per square centimeter).

Breeze

[MikeD83]

"Meanwhile, the cloud of electrons would be alternatively attracted to and repelled by adjacent electrodes. Alternating the voltages on the electrodes creates a cooling breeze because the moving cloud stirs the air."

Amazing, Purdue is developing the same technology used in such high tech devices as the Ionic Breeze air purifier.

Hot and bothered!

[3770]

Not that I claim to have a solution to the problem with overheating processors. But the power consumption of computers are starting to bother me.

I used to want the fastest computer around. But a few things have changed I guess.

First of all computers are starting to be fast enough for most needs.

Secondly, the way I use computers has changed with always on Internet. I never turn my computer off because I want to be able to quickly look something up on the web.

I also have a server that is running 24/7. Most of the time it is idling, but even when it is working I don't need it to be a speed demon.

So it is starting to be really important for me that a computer doesn't use a lot of power. I don't know if it affects my electric bill in a noticeable way, but it feels wrong.

Alliances

[Brainix]

The alliance proposed in the article, to me, seems similar to the AIM Alliance of the early 90s. Several companies united in a common goal. I've heard the AIM Alliance failed because competitors united in a common goal remain competitors, and as such tend not to fully disclose "trade secrets," even to further the common goal. If this proposed alliance takes off, I fear it will suffer the same fate as the AIM Alliance.

But can you make a cluster of them...?

[ites]

Not a joke.

The future is multi-core / multi-CPU boards where scaling comes from adding more pieces, not making them individually faster.

Yes, chips will always get faster and hopefully cooler, but it's no longer the key to performance.

heat has already been MOBO issue

[KarmaOverDogma]

Especially for those of us with newer motherboards who want a completely silent system with as few fans as possible

First it was CPUs with cooling and big/slow/no fans and big heatsinks, then PSUs GPUs and now MOBOs. My current custom box (now 14 months old) was built to be silent and I had a hard time settling on a motherboard that was state of the art, stable, and still used a passive heatsink to cool the board chipset fan-free. I finally settled on an Asus P4P800.

I can definately believe heat becoming even more of an issue. For those of us who want power/performance and quiet at the same time, this will become even more of a challenge as time goes on. I for one hope not to rely on expensive and/or complicated cooling devices, like peltier units, water pumps and the like. I hope the focus is on efficient chips that only clock up/power up as they need to, like the pentuim M.

my 2 cents.

10 times more heat?

[kennycoder]

Whoa that's cool, now it means no more petrol is needed.

If i take out my CPU cooler it reaches about 100'C. Now lets see, 100 x 10 = 1000'C in only 15 years of chip industry. If we manage out to put this heat into work, lets say we can have 'PC + hairdryer' packages or 'PC + free home-heating' winter offers or even 'PC - burn-a-pizza' boxes. Think about it, its only good news.
Funny, -1

Re:A strange question, but...

[myukew]

it's the size.
compare the typical light bulb with the typical wire running through your house. the light bulb gets hot because of the thin wire.

Re:Why is heat reclamation not worth it?

[zippthorne]

The maximum amount of useful work you can extract from a heat engine with two temperature pools has been derived and is known as Carnot Efficiency:

eta = (Thot - Tcold)/Thot.

using absolute temperatures (Kelvin or Rankine)
So assuming the limit is Thot = 60C = 333 K and Tcold = 25C (average room temp) = 298 K, The maximum efficiency would be 10%. Assuming further that 100W is lost by the chip alone, only 10W would be potentially recoverable. Unfortunately it gets worse: The Carnot cycle is theoretical and no real carnot engine could ever be produced. There are some very efficient cycles available (stirling and rankine come to mind) however none can exceed the carnot efficiency.

It also gets worse as you make the engine smaller. Consider the tolerance of pistons or turbines. Suppose you must leave 1mm of gap between surfaces. For large engines this is no problem, but as the machines become smaller, the minimum gap becomes a greater percentage of the total area.

Machines to extract energy from such a small source at such a low temperature difference have significant theoretical inefficiencies before you even get to the practical ones. This does not mean that you can't recover any of the "wasted heat" but only that you've pretty much gotten all the useful work out of it that you can and recovering the rest would be very impractical.

Have you ever eaten a lobster? did you suck the meat from the legs?