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A clean computer is a happy computer

 
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rjlittlefield
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Joined: 01 Aug 2006
Posts: 17390
Location: Richland, Washington State, USA

PostPosted: Tue Jun 04, 2013 5:29 pm    Post subject: A clean computer is a happy computer Reply with quote

Today I had a personal experience with overheating of a CPU.

The story began last night, when I was demonstrating to my wife that my computer fan would run a lot faster when I was stacking than when the machine was idle. After a few minutes of running Zerene Stacker, it would wind up to roughly the loudness of a small hair dryer. She thought that was interesting.

This morning, she asked if I was stacking again, and when I said "no", she pointed out that my computer seemed rather louder than it ought to be in that case. I agreed that it did, and in fact I was getting a little tired of the fan noise. Perhaps a good vacuuming would be in order.

So I powered down the machine, unplugged all the peripherals, removed the side panel, and set to work.

There did not seem to be a lot of dust inside the box . . . until I looked between the blades of the fan mounted directly on the CPU heat sink.

There I was surprised to see that about half the slits between vanes on the heat sink were completely covered over with a thin layer of dust. It looked a lot like snow bridges over miniature crevasses. Yep, surely that would reduce air circulation.

My first thought was to remove the fan so I could get clear access to the heat sink. But the fan housing was screwed so tightly to the heat sink that I couldn't get it loose.

Switching strategies, I searched out a 1/2" paintbrush and used that to reach between the fan blades to brush the heat sink while vacuuming the area as best I could.

A few minutes work and the heat sink looked almost as good as new.

After cleaning, the machine will now run two copies of Zerene Stacker simultaneously, pinning the cpu at 95-100%, while the fan makes no more noise than it did at idle before the cleaning.

Problem solved. "A clean computer is a happy computer."

Come to think of it, given smart power management software there's potentially some advice that would otherwise sound like an urban myth:
Quote:
"To make your computer run faster, open it up and give it a good cleaning. The processor can't run as fast when there's too much dust on its feet." Wink
--Rik


Edit: change title


Last edited by rjlittlefield on Wed Jun 05, 2013 1:42 pm; edited 1 time in total
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elf



Joined: 18 Nov 2007
Posts: 1283

PostPosted: Tue Jun 04, 2013 7:06 pm    Post subject: Reply with quote

Didn't happen without a macro shot showing it Smile
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rjlittlefield
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Joined: 01 Aug 2006
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Location: Richland, Washington State, USA

PostPosted: Tue Jun 04, 2013 7:27 pm    Post subject: Reply with quote

I had the same thought. Alas, I took no pictures before I started the work. No audio recordings either. Sad

--Rik
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Chris S.
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Joined: 05 Apr 2009
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Location: Ohio, USA

PostPosted: Tue Jun 04, 2013 9:39 pm    Post subject: Reply with quote

Rik,

Speaking as someone who (for my sins) maintains way too many computers, I think you've brought up an important subject. Let me try to add what I hope will be a useful detail or two.

The computers I use every day get a thorough cleaning about every three months--and truly need it that often. You'd be surprised at the big clouds of dust that come out during these cleanings. I maintain quite a few other computers, and whenever one comes my way, the first thing I do is clean it out. I find that most other people's machines get filthy, too.

Dust in a computer can certainly make it noisier, but this is a side effect of the bigger problem: The dust interferes with air flow, and certain parts of a computer generate a lot of heat and will be damaged without constant airflow to dissipate it. If the heat builds up too much, bits of the computer can go "pop" and stop working, or at least have their working lives drastically shortened. Most motherboards have several temperature sensors in them. When things get too warm, a motherboard will--if equipped with variable speed fans and the ability to control them--turn the fans up. (Not all systems are set up this way--some run the fans full out at all times.) This is the cause of the increased noise. The next thing most computers do is slow down some of the heat-producing components for their own protection; slower processing can mean slower production of heat. And the next thing a computer does is shut down; a huge percentage of sudden shutdowns are heat-related. And even if the temperature doesn't get high enough to cause the computer to shut down, the slow-cooking of internal components can lead them to fail permanently.

Vacuum cleaners--even powerful ones--do a poor job of getting dust out of a computer. A brush is useful, but usually misses a lot of the worst dust. To get a computer really clean, try taking it outside and blowing it out thoroughly with a can of compressed air. The resultant cloud of dust is often astonishing! (Rik, there is a strong chance that if you do this, even after your brush-cleaning just now, you'll still get a cloud.)

I got tired of going through numerous cans of compressed air, so purchased a Metro Vacuum ED500 DataVac electric duster, a powerful electric blower. This gizmo is like a hand-held tornado, and is very handy.

Quote:
My first thought was to remove the fan so I could get clear access to the heat sink. But the fan housing was screwed so tightly to the heat sink that I couldn't get it loose.

It may be useful to differentiate between the various fans found in computers. This sounds like the "CPU fan," which sits above the heat sink that cools the CPU. (Other fans would be: "Case fans" that move air through the computer case; the fan that pulls air through the power supply; and the fan found on many graphics cards.) The CPU fan should be treated with particular respect. Most of them are--as you found in your system--tightly integrated with the CPU heat sink. Disassembling the two involves some risk of disrupting the heat sink's physical contact with the underlying CPU. This contact is a bit tricky--mess it up, even a little bit, and the computer system may become prone to sudden shutdowns, and/or become slower. Such a problem is not all that hard to fix (though it may be hard to diagnose), but requires a tube of heat sink paste, a good solvent, and a bit of know-how--so while it's not the end of the world, many people would find it inconvenient.

One problem area for dust is the heat sink in the graphics card. I find it very important to remove the graphics card from its slot and blow it out separately. This is now part of every cleaning, because I've seen it be the make-or-break step for fixing several unreliable systems.

Also, laptop computers are a special case--they are vastly more prone to dust problems than desktop/tower computers. Typically, if your laptop computer has seen two or more years of frequent use, and the fan is getting louder or being loud more frequently, it probably has a dust issue. If it is getting slower or experiencing sudden shutdowns when heavily used, these are also indications of a dust problem. Imagine a thick wad of felt insulating the CPU or graphics processor--which fails when hot--and you'll have the picture. Unfortunately, the difficulty in clearing such a problem varies widely with brand and model; it might be an mindless 15-minute job, or a hair-pulling 10-hour ordeal.

(And for whatever it's worth, I once saw Dell quote $400 for a laptop dust problem that took me 15 minutes to fix. Taking only 15 minutes is one of the afore-mentioned sins. And I've seen several laptops with shutdown problems that independent repair shops either could not replicate or not diagnose; each was a dust-related overheating issue, and each proved fixable. Fixing these was another set of sins--if you find that you can do this sort of thing, don't tell anybody, unless you want constant interruptions in your real work.)

--Chris
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g4lab



Joined: 23 May 2008
Posts: 1423

PostPosted: Wed Jun 05, 2013 10:44 am    Post subject: Reply with quote

I second everything Chris S just said.
Back in the day they, used to teach that for many electronic components , the MTBF was halved for for every 10 degrees C of temperature increase.
Probably more important now , since the function of all our digital goodies depends on circuit traces with submicron dimensions.

I just had a failure of a very high priced Fujitsu Siemens workstation that I got surplus from Zeiss. The CPU shorted out and killed the power supply.
CPU was easy to find a replacement for. The power supply had to be gotten from Germany. I had done a pretty good job of keeping this critter clean so I don't think dust was the ultimate culprit. But something thermal probably was.
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Rylee Isitt



Joined: 13 Apr 2012
Posts: 474
Location: Canada

PostPosted: Wed Jun 05, 2013 11:53 am    Post subject: Reply with quote

In addition to simply cleaning them out as mentioned, I've also found that the conductive pads placed between the CPU or GPU and heat sinks are often not very good. In some cases I've replaced them with arctic silver thermal paste and noticed, at least anecdotally, a fairly large improvement.

On desktops I've owned, I've been able to get cases with washable filters on the air intakes. This allows you to remove the filters, take them outside, and beat them to get all the dust out (I never went as far as washing them). This does a pretty good job of preventing dust buildup on the heat sink vanes. It's not just about air flow being reduced - the dust insulated the heat sink vanes and prevents heat transfer to the air.

It would be nice to see a feature like that in a laptop... but I expect it would be a rare feature, and there are many other considerations to make when buying a laptop for a intensive process like stacking that you may not be able to justify buying a particular model just to get an air filter in it.
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discomorphella



Joined: 01 Oct 2006
Posts: 586
Location: NW USA

PostPosted: Wed Jun 05, 2013 12:50 pm    Post subject: Reply with quote

In addition to motherboard temperature sensing / interlock systems, if you have a CPU from the past few generations, it will be thermally throttling itself to avoid fatal heat damage. This can take several forms, all of which will reduce CPU performance, potentially quite drastically. Your TTF (reliability) won't be affected, as the CPU is going to throttle itself to maintain its internal temp within the rel limits, but it can slow itself down and / or turn off bits of itself (including shutting down altogether) to keep itself safe. Older CPU's could in fact blow themselves up, as I have accidentally demonstrated to myself in lab a long time ago. Newer ones have built-in temperature sensing.

David

p.s. this describes some of the on-die thermal management capabilities, in case anyone is interested

http://www.intel.com/content/www/us/en/intelligent-systems/cpu-monitoring-dts-peci-paper.html?wapkw=cpu+thermal+throttling+spec
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rjlittlefield
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PostPosted: Wed Jun 05, 2013 1:37 pm    Post subject: Reply with quote

Thanks to everyone for the excellent explanations and suggestions.

In keeping with the general thrust of comments, I've changed the thread title. Instead of "A clean computer is a quiet computer", it's now "A clean computer is a happy computer".

--Rik
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scottburgess



Joined: 24 Mar 2013
Posts: 20
Location: California

PostPosted: Wed Jun 05, 2013 1:48 pm    Post subject: Reply with quote

I build my own computers, and all the housings I use have good, removable dust filters on them. Saves a lot of time and trouble.
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g4lab



Joined: 23 May 2008
Posts: 1423

PostPosted: Wed Jun 05, 2013 3:41 pm    Post subject: Reply with quote

I have often washed filters. I have even , QUITE often washed electronics boards including computer motherboards.

The trick is to rinse them with nice clean hopefully soft water.

Then do a final rinse with water from a Deionized system. I give them a thorough rinse with water from a "water polishing " station which purifies the building DI water to 18.2 megohm-cm resistivity. (that is as good as it gets)

Then I blow it off with air or a duster and let it dry for several days. If I don't have several days I may use a heat gun to help it get dry.

Haven't kilt one yet doing that and have brought a couple back from the dead. (one a single board computer, in an instrument, had water leaking on it all weekend and and ceiling tile residue that I had flush out. Still works.


Last edited by g4lab on Wed Jun 19, 2013 9:56 am; edited 1 time in total
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Chris S.
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PostPosted: Thu Jun 06, 2013 1:16 am    Post subject: Reply with quote

scottburgess wrote:
I build my own computers, and all the housings I use have good, removable dust filters on them. Saves a lot of time and trouble.

Scott, I build computers, too (about six per year, on average), and consider removable dust filters a double-edged sword. Even when the filters are clean, they can reduce air flow, so you may have to turn the fans up a bit to keep the system cool, which can increase noise. And the filters can get clogged with dust very quickly, which reduces air flow even more. Also, in my experience, filters don’t prevent all dust from entering the computer, so the computer still needs occasional internal cleaning—though not as frequently as if the filters were not in use.

For my own computers, I choose not to use dust filters. For the computers I build for others, this is one of the issues we discuss beforehand. If the user prefers to do frequent cleaning of filters and occasional internal cleaning, I use a case with dust filters; if the user does not want to perform frequent filter cleaning, but is OK with internal cleaning being needed somewhat more often, I use a case without filters. Most people I deal with have gone the “no filter” route. This is, I think, a TANSTAAFL situation--we can't eliminate the dust issue, but can exercise some choice over how we prefer to deal with it.


Rylee Isitt wrote:
. . . I've also found that the conductive pads placed between the CPU or GPU and heat sinks are often not very good. In some cases I've replaced them with arctic silver thermal paste and noticed, at least anecdotally, a fairly large improvement.

Rylee, I think that the paste included with at least the Intel-brand CPU fans has improved a lot in recent years. Back when it was "pad-like," replacing it with Arctic Silver thermal paste seemed to make a difference, but I’m not so sure this is true anymore (the Intel CPU fans I’ve installed in the past few years have had something more like paste, rather than a meltable pad). About four years ago, I built a pair of computers out of precisely the same components, but replaced the Intel heat sink paste in one with Arctic Silver. Testing the two machines, there was no noticeable difference. Of course, there are many brands of CPU fan other than Intel, and their heat-sink paste may or may not be as good.


Quote:
It would be nice to see a feature like that in a laptop... but I expect it would be a rare feature, and there are many other considerations to make when buying a laptop for an intensive process like stacking that you may not be able to justify buying a particular model just to get an air filter in it.

Perhaps sadly, I’ve never seen a removable air filter on a laptop, and have serviced a lot of laptops. What one may be able to do (though with difficulty), when buying a laptop, is to try to purchase a model whose heat sink is easy to clean. Unfortunately, this information is not commonly found in reviews, marketing materials, or official support documentation. If the laptop model has been out for a while, a Web search on the model name and a term such as "disassembly" may bring up somebody showing how to do a tear-down. If you find that, you can look at how many steps it takes to get to the heat sink, and how difficult those steps are.

A number of Lenovo Thinkpads (once known as “IBM Thinkpads”) have impressed me over the years with their build quality, and attention to issues that most buyers wouldn’t think of. Kind of a “we do it right even where nobody looks” approach, which is singular among laptop makers, in my experience. (And the diametric opposite of Dell, which seems to have “cutting corners where people don’t look” down to a science.) A few years ago, I purchased a Lenovo Thinkpad on behalf of a client, and when I was preconfiguring it, noted that it had one more access panel than most laptops on the bottom. There is, of course, generally an access panel for installing additional RAM, and one for replacing the hard drive (which may be on the side, not the bottom). I wondered what the additional panel was for, and removed its single holding screw to find out. Good heavens, it provided instant access to the heat sink, allowing easy dust removal! Wow, somebody appeared to have engineered the machine to be easily maintained. I have since purchased several more Lenovo Thinkpads on behalf of clients, and one for myself. Not all have this access panel, but some do. Whether a particular model has it or not is difficult to determine, until one has a specimen in hand.

BTW, the absolute worst laptops I’ve seen for internal cleaning have been Toshibas. I don’t know whether their current engineering is as maintenance-unfriendly as the models I’ve seen, because my nightmarish experiences have made me refuse to consider recommending their products. Imagine a car where you need to disassemble every single component, from glovebox to engine, to change the oil—you will not be far off.

--Chris
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spongepuppy



Joined: 26 Nov 2012
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PostPosted: Tue Jun 18, 2013 9:45 pm    Post subject: Reply with quote

I recently had to completely disassemble a Dell Vostro 3500 laptop to clean the heatsink. It was a singularly unrewarding experience.

vConfusedv

Why does Dell hurt us?
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DQE



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PostPosted: Fri Jun 21, 2013 5:37 pm    Post subject: Reply with quote

We have two cats who shed incessantly. This plus the usual household dust creates a bad problem for my tower PC.

My solution is to use a large but soft hair brush to clean the fine wire mesh screens that sit in front of the large case and other cooling fans in my PC. I do this weekly, reminded by an iPod alarm. This seems to prevent *most* of the dust and cat hair from entering the case and depositing onto the circuit boards.

Once or twice a year, after using compressed air to blow off most dust, I use a slightly damp cloth to very gently remove most of the remaining (very fine) surface dust from the top and bottom of accessible circuit boards. Compressed air might be enough - I am uneasy about wiping the boards with a slightly damp cloth but the surfaces dry very quickly.

This cleaning process (esp the final circuit board cleaning) stopped otherwise unexplained crashes my PC had begun having after a year of use. I speculate that the fine dust was shorting out or making some of the circuit boards' components or connections vulnerable to static electricity. I of course unplug the PC before trying to remove the dust from the circuit boards.

The very fine mesh screens that cover the large entrance ports of each of the main case fans as well as the DVD drives slots seem to catch the vast majority of dust from entering my PC tower's case, but they do need to be brushed clean about once a week. They are a built-in feature of my Antec PC case or perhaps the fans as assembled by Puget Systems (a custom PC company near Seattle).
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Doc.Al



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PostPosted: Tue Jun 25, 2013 4:18 am    Post subject: Reply with quote

I had a problem recently with my PC shutting itself down after running for several hours and assumed that this was an overheating CPU problem. I checked inside the case and the CPU heatsink and fan looked clean and was seated correctly, and so I prepared myself for the worse case of having to consider a new computer.

However, I decided to give one last go at fixing the old one, and after advice from an IT forum, I loaded temperature monitoring software (I used something called Hmonitor as it was free) to see how hot the CPU was getting. It turned out that the CPU was running at a good temp, but it was the video card that was running hot (up to 110°C at one point). A quick dismantle, clean and rebuild (with fresh thermal paste) and the problem has been solved.

I would recommend using some form of temperature monitoring software if you are having overheating problems as this quickly identified the culprit.
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