Slashdot Mirror
IBM Doubles CPU Cooling With Simple Change
Ars Technica is reporting that IBM has discovered a new cooling breakthrough that, unlike several other recent announcements, should be relatively easy and cost-effective to implement. "IBM's find addresses how thermal paste is typically spread between the face of a chip and the heat spreader that sits directly over the core. Overclockers already know how crucial it is to apply thermal paste the right way: too much, and it causes heat buildup. Too little, and it causes heat buildup. It has to be "just right," which is why IBM looked to find the best way to get the gooey stuff where it needs to be and in the right amount, and to make it significantly more efficient in the process."
I find it kind of funny that after all these years of proper modders polishing the hell out of thier heatsink and spreader, along comes IBM and makes them rough and it cools better :)
That said, its probably only better in the average case but less good than the ideal case due to the fact of having less contact in the microgroove areas.
"You can now flame me, I am full of love,"
sure, it does. Less fans = less power consumption.
"You had this look that of an angel, it was such a bad disguise" --Dishwalla
Everything about putting together a new computer, or installing a new chip set is pretty straight-forward, except for the thermal paste. While nothing is to complicated, it is the only factor that is not clearly right or wrong depending on how you do it. Couple that with it being the hardest thing to reach in/on the computer, I am glad to see some changes are being made. It would be nice to simplify the process down to be just as easy as setting the fan on top of it.
Invexi - a Phoenix, AZ based web design and web development company.
Namaste
They etched a series of microgrooves on the surface of the headsink to act as a channel for excess thermal paste. This is supposed to make much better contact than a smooth surface.
"You can now flame me, I am full of love,"
When i ordered my Artic Silver compound, the website had some instructions on how to apply the paste depending on what type of CPU you own. These instructions can be applied to any kind of thermal paste.
here's a link.
http://www.arcticsilver.com/instructions.htm
Previewing comments are for sissies!
this isn't taught where I work, and as a result oftentimes we get the units we fixed sent right back for overheating and shutting down. Pop off the heatpipe and fan assemly on the laptop mtherboard, and whoa-nelly! The ENTIRE SURFACE OF THE PROCESSOR'S COATED with thermal paste.
Each tube of thermal paste we get contains about 4CCs worth of thermal paste - MORE than enough to handle about seven or so CPUs. Instead, the entire tube gets shot onto the proc, because the syring is labeled "Single use only" (Yea, that's what I thought.)
Roughing the surface of the core casing seems like a good idea, but I dunno, most thermal compounds are rather gritty as is and wont' fit into those uber-tiny grooves. A more liquid thermal ahesive would see to be a better idea if you're going to mar the surface of the core's protective casing, I would think.
Still waiting on Serviscope_minor to wake up to fucking reality and realize that Jessica Price isn't going to fuck him.
If you'd ever taken the time to actually try lapping the heatsink and heat spreaders rather than making fun, you would notice a significant drop in temperatures.
Even today with the new Core 2 Duo CPUs, the IHS have been found to be concave. Personally having lapped my CPU, the load temperatures dropped 10 C - nothing to sneeze at.
This article is more about the refinement of a technique. Notice how the article states "micrometer-length trenches", and not surfaces filled with ridges you can feel by running along it with your finger nail.
Most overclockers know that you get diminishing returns the further you polish the surfaces anyway.
When will someone get a clue and power CPU fans with Stirling Engines?
All generalizations are false, including this one. Mark Twain
It doesn't help power consumption, but better cooling = less fans = less noise.
Actually, it helps *very* much with power consumption. Usually, resistance goes up as the tempeature does. For example, this is what an incandescent bulb relies on. What this means, is that as the chip gets hotter, it will resist more, causing a need for higher output to get the same usuable energy. By cooling the chip, its resistance stays low, allowing a higher efficiency in power usuage. IOW, less heat, less energy required.
Secondly, as another commentor pointed out, there's the fans that are use to cool it down, which indirectly allows for a lower power-consumption.
Have you read my journal today?
IBM looked to find the best way to get the gooey stuff where it needs to be and in the right amount
I know some sites with plenty of AVIs that will show you how to do that...
Story is here.
I could be wrong, but I believe that the polishing was done back in the day when the core was exposed (back in the Athlon days) so that the heatsink would make the best contact it could with the core. The core was such a small dense area that the best contact possible was needed. Now that everyone has a spreader on their core(s) the spreader itself does most of the immediate heat relieving and the contact between the spreader and cooler is much larger. With the larger area of contact using the super polished method it is much harder to get an even 'sandwich' across the entire area of the spreader, thus the move to the rougher finish.
IIRC, semiconductors don't work that way; Their resistance tends to decrease with increasing temperature.
http://outcampaign.org/
And if you did, you will know that the thermal paste itself is very inefficient for its thermal properties compared to the metal surface of the heatsink. What IBM has found out is a way to cheaply and quickly put a heatsink on the CPU which uses less thermal paste (1/3 less), which results in a 50% increase in cooling capability of the heatsink. What they don't tell you is that the idea way is to spread the paste using a hard straight edge with a uniform height over the cpu itself and apply an extremely smooth heatsink to this. But, this process takes too long for it to be worth it in mass production. It typically takes me 2-3 minutes to spread the thermal compound and mount the heatsink on a chip. In a production line, it needs to take 5-20 seconds.
All IBM has done is develop a better method compared to their previous less efficient method. It is still worse then someone taking the time to lap the heatsink level and smooth and properly spread the true correct amount of thermal compound on the CPU then IBM's new method. To give you an idea, IBM is still using around 10x more thermal compound then is used in hand built systems. As you saw, a 1/3 reduction resulted in 50% increase in performance. Imagine then what a 9/10 reduction would result... The compound itself has the highest/worst thermal co-efficient in the cooling system. It makes a lot of sense that getting less of it in there will increase the performance. The key to reducing this substance is having a heatsink that will fit perfectly flush with the CPU.
We were all warned a long time ago that MS products sucked, remember the Magic 8 Ball said, "Outlook not so good"
First, you should have done some research. I don't care how much was in that syringe, it was probably too much -- you only need a small amount of thermal paste, just enough to fill the tiny gaps between a CPU and the heat sink.
Second, removing the case's cover will completely disrupt the air flow inside. If that actually makes your CPU cooler, you have some serious problems with the way your fans are set up. If they're set up so that they're constantly pushing cold air over the CPU and hot air out of the case, it should, in fact, be cooler with the cover on.
It is less funny when you realize that the roughness stands in a direct relationship to the size of the metal bits in the paste. If all you can get between the valleys of a roughened copper heat sink is the binding mass instead of the silver particles because their too large then you will have a rather bad heat conduction. If you however get the surface rough and the silver particles are as small as nano particles, then you might get what IBM has achieved: much more surface and lots of contact.
Most cheap PC cases are designed utterly without thought to proper airflow.
Also most times fans blow in from the front, across the drives, where the air is preheated.
Most cheap PC cases will cool better when open, sad but true.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
Make the top of the cpu's copper slug corrugated or dimpled, sin(x) and sin(x) + sin(y) respectively. Doing this will create more surface area for heat transfer. You can then use a piece of malleable gold foil to fill in any gaps.
One of those why didn't I think of that moments... D'oh!
Do you really think that in 2 minutes with a razor blade that you can get a more uniform thickness than machinery which can be accurate to millionths of an inch?
Multiply that by a few [hundred] million computers and suddenly you're saving a few [hundred] MW. See also: this post.
I'll never understand why people are so quick to dismiss seemingly trivial power savings. What's trivial on the single-person level is not-so-trivial on a global level.
Mod parent up. If I look at the picture, where it says "chip-cap" and the paste is between the chip and the cap, then this is definitely a different area than between the chip cap and the heat spreader. Actually, the front page story reads "Overclockers already know how crucial it is to apply thermal paste the right way: too much, and it causes heat buildup." Of course, before that, a really good reader had already read "between the face of a chip and the heat spreader that sits directly over the core." But since this is Slashdot, most comments seem to be off the mark.
I hope every one realizes that this has nothing to do with the goop you put on before you snap your heatsink on. This is the thermal grease that goes on the die before they put the cap on processor.
Erm... You might not have noticed, but this technique is for the heat transfer between the CPU chip and the heat-spreader, NOT the heatsink bolted on later. This is inside the chip package, and underneath the metal plate you're thinking of as the CPU contact. You have no access to this interface, since it's sealed in the chip carrier. This interface uses a completely different compound as compared to the stuff you use to attach a heatsink, and the design they've come up with actually does work considerably better for this application, in addition to improving heat transfer, it also reduces application force, improving manufacturing yield, and therefore reducing cost.
Here's a thought, since you appear to be a fairly fluent 'modder' - ... well gold (which is pretty good.) I'd envision that if you got the lap right on both the CPU and the heatsink, you could do it as a single dry leaf (not as a paste) and give it a few minutes to settle in under pressure, turn on the CPU to heat things up a little until it seated in better (don't burn it in right away) and watch the CPU temps - I would be REAL interested in hearing how it went.
What if, after lapping both the heatsink and the CPU (to a mirror flat finish, or not, probably worth experimenting) instead of thermal paste you used gold leaf foil? Basically it is gold pounded ultra thin (in the 100 nanometer range, such that one square meter is made from 2 grams of gold), flat, would flex/bend to conform to the two surfaces and has the thermal transfer quality of
Try it with a system you are retiring anyways, see what kind of difference it made. Never know, since a piece of gold leaf isn't prohibitively expensive (a small piece would cost you less than a dollar, get a few pieces while you are dialing in the process.)
Glonoinha the MebiByte Slayer
Very true, but the issue I was getting at was that the thin layer of gold would be instead of the thermal grease, and would serve to create the 'gasket' between the CPU and heatsink, increasing (significantly, if my theory is right) the thermal transfer as the gold would have a much higher coefficient of thermal conductivity than even the best paste. The reason I suggested gold is that gold can easily be purchased in small quantities of gold foil, the gold foil is ~very~ flexible / malleable and would serve to fill in all the microscopic gaps between the CPU and heatsink creating a thermal bridge in the process (which is the purpose of the paste), thus making the cooling solution quite a bit more effective.
In theory.
Anybody want to try it, perhaps on some older hardware?
Glonoinha the MebiByte Slayer
Sounds like it would not work well:
3 10
"To be effective a TIM combines properties to minimize the total interface resistance. High conductivity (200-420 W/mC) materials, like copper, silver, aluminum and gold, maximize thermal conductivity, but do not flow into intimate contact because of the relative lack of compliance so the interface resistances are very high and the overall performance is poor."
http://www.indium.com/_dynamo/download.php?docid=