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."

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.

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.

hardware DRM

[GoatPigSheep]

When I think of future problems that will happen to hardware, Hardware DRM comes to mind.

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.

Why is heat reclamation not worth it?

[EbNo]

I'd like to hear from some engineering types about why we can't use the excess heat from CPUs to do useful work. I know virtually all large-scale methods of generating electricity involve generating large amounts of heat through some process (nuclear reactions, burning coal or oil, etc), using it to create a hot gas, which turns a turbine, generating electricity.

I also have some vague handwaving idea that there are processes for generating electricity that have to do with harnessing temperature differentials, but I really don't know what I'm talking about.

Anyway, why can't we have little gas turbine generators (or some other method) in our machines that reclaim some of this lost energy, instead of wasting it? Seems like the aggregate energy amounts would be pretty large.

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.

Missing an option?

[andreMA]

It sounds like (RTFA? who, me?) they're focussing on either reducing the amount of heat generated or finding ways to dispose of it more efficiently. Important, sure... but what about developing more heat-tolerant processors? If things ran reliably at 600C, you'd have an easier time moving x amount of waste heat away to the ambient (room-temp) environment, no? Proportional to the 4th power of the temperature difference, no?

Or perhaps I'm grossly physics-impaired.

Re:Hot and bothered!

[Hadlock]

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.

well a quick google says it's about five cents per kWh... assume your server spins down the disk drives when idling, and your monitor turns off when not in use; you're probably averaging 200watts an hour. That comes out to be abour $6.72/month in electricity, or $80 per year.

If you're looking for power savings, an old laptop with an external hard drive only consumes about 15W at idle... or about $6 per year. In what you spend in two years running you "server" you could have a decent laptop + gianormous 120 gig external drive as your server, and look things up "instantly" from your bedside.

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:diamond cooling

[N3Bruce]

Being able to conduct heat internally is a major asset. Conductivity of heat is based on the difference in temperature between the heated end and the unheated end of a material of a given shape and surface area. Think about this junior high school level experiment with a cigarette:

A 1 gram mass of loosely packed tobacco is wrapped into a paper sleeve .5 cm in diameter and 10 cm long and is a very poor conductor of heat. A match is applied to one end for a few seconds, causing the tobacco to smoulder red-hot, while the other end is cool enough to touch. The small area of combustion is kept warm enough to sustain combustion by the insulating properties of the tobacco and ash surrounding it.

If you repeat this experiment with an aluminum rod of the same size, such as an aluminum nail, the heat from the match would quickly conduct the entire length of the rod, making it hot to touch within a couple of seconds. While the rod would get hot enough to be uncomfortable to hold, the end which was heated by the match would definitely not be hot enough to light a cigarette, unless the whole rod was heated red-hot.

This simple experiment demonstrates the limits of heat sinks. While aluminum is a good conductor, it isn't perfect. The area closest to the heat source will always be hotter than the areas near the ends of the fins. The quicker heat can be conducted away from the area next to the heat source, the cooler that area stays. A heat sink made from a material that is a perfect heat conductor will have a uniform temperature throughout, and keep the temperature next to the heat source the same as the tips of the cooling fins.

Junction temperature of electrical components is the critical parameter in heat sink design. A heat sink today may have a temperature of say 50C at the ends of the cooling fins, but be 200 degrees at the chip/heatsink interface, which is a guesstimate of the maximum safe temperature of a junction. A perfect heatsink material might only need to be half the size or less to keep temperatures at safe levels. Heatsinks to dissapate larger amounts of heat could be scaled more easily than is currently possible.