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 Post subject: Uncontrollable Intel Speedstepping... culprit: lint!
PostPosted: Tue Nov 13, 2007 5:42 pm 
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Just thought I'd note this here in case anybody's having similar issues...

I'm putting it in the folding forum because I'm not sure anybody else at SPCR would have a good reason to try and run their CPU at full whack all the time.

My work machine is a Dell Precision M65 notebook. I've been running the Windows SMP client on it. By chance, I happened to be running CPU-Z a few days ago and discovered that the processor was stepping down from 2000MHz to 1666, 1333 or even 1000 whilst F@H was running.

Now, this shocked me for two reasons:
1) I had assumed that the processor would run full speed if fed with work by processes like F@H.
2) I thought I had set the machine to run at "High Performance" when on AC.

I thought maybe the F@H processes were set at too low a priority to keep the processor at full speed, so I increased the priority. No good, it was still stepping down. "Grr! Stupid windows," I thought...

So off I went and learned about the windows command-line power management utilities. All well and good, I set the thing to "none" for cpu stepping on AC, assuming that'd solve the problem. No such luck. In theory, the settings were fine, but in practice, it was still inexplicably stepping down...

So when I was at work today, I was thinking about it all and fired up cpu-z again. Then I noticed that the thing wasn't throttling anymore. Sat solid at 2000MHz for hours. Then I realised, the laptop sits raised 4" on a perforated steel laptop stand at work, but flat on my wooden desk at home. I came home and raised it up by putting a 1/2" book under each corner and bingo! no more throttling (incidentally, I recommend the ExpressExec series of management books for this purpose - they're bloody useless for anything else).

So it looks like, even in a fairly cold study, the Precision M65 needs extra airflow to the intake at the bottom of the machine to cool itself properly. Surprising, since the rubber feet already lift it a good few mm off the surface. I'm tempted to take it apart and clean out any dust before reseating the heatsinks with some good thermal compound, but I don't want to screw it up, since it belongs to work, not me! I've downclocked the GPU, since I understand it uses the same heatsink as the CPU.

I'm not overclocking it and it's not very old. CPU/GPU overheating could explain some instability I've been suffering from time to time, as well. Not too impressive for what's supposed to be an engineering workstation.


Last edited by adam_mccullough on Thu Nov 15, 2007 8:03 am, edited 2 times in total.

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 Post subject:
PostPosted: Tue Nov 13, 2007 7:39 pm 
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Definitely open it up and dust it out. Don't bother messing with the thermal paste, that doesn't go bad.

An immediate thing you can do is air-canning or vacuming the vents right now, if there isn't alot of dust then that should do the trick. If there is alot then you have to open it up.


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PostPosted: Tue Nov 13, 2007 7:41 pm 
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Interesting info.

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 Post subject:
PostPosted: Wed Nov 14, 2007 3:30 am 
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Graphics cards throttle with heat as well. You can see this as an error in event viewer with L1 -> L2 transition (or something similar). Just curious did this create an event in event viewer?

And yes, dust it out. It can help to take the cpu cooler out and give it a proper clean. It is usually helpful to look online for someone else who has done it on the same machine.


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PostPosted: Wed Nov 14, 2007 10:52 am 
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Had a quick look in the vents, and it doesn't look like there's any significant dust buildup. Hmmm...

Once I've done a full backup I'll take it apart and see what's what. Since I've lugged this machine all over the world for work, I'm wondering if maybe I've bumped it sometime and unseated the heat transfer block from the cpu?

It definitely doesn't happen when the machine's raised. I wonder who had the great idea of putting the only intake on the bottom surface of the casing.

Update: having found a program that'll monitor the temperatures in this machine, I've found that the core temps are generally around 80C under load; they rise just over 80, then the CPU throttles down to drop them under 80 again. Idle temps are around 60-65C. Totally convinced now that this is the problem - other articles about this laptop mention core temps around 45/65 idle/load. I think tomorrow I'm gonna open her up and see what gives.


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 Post subject:
PostPosted: Thu Nov 15, 2007 2:41 am 
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Good luck and let us know how it goes. Your temps at the moment are much to high. Make sure you have thermal paste and isopropyl alcohol (or similar, to clean the cpu).

But I wouldn't be surprised if it is just dust accumulation. My parents laptop was having similar problems in the summer and a good clean, and reseating of the cpu heatsink fixed it.


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PostPosted: Thu Nov 15, 2007 8:01 am 
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Good call on the dust front. I was sceptical, since the visibility through the vents seemed good and I couldn't really see any dust buildup. But when I opened the machine up, there was a huge pad of dust/lint completely blocking the duct from the fan to the main heatsink, in a spot not visible from outside the casing.

I took photos, which I'll upload later.

With the fan at the same settings as before, the CPU now runs at 51C under load. When I set the fan to run at low speed, load temp rises to about 56C. I'm amazed at how quiet this machine has suddenly become.

As an added bonus, the GPU and chipset (both attached to the same heatpipe assembly as the CPU) have gone from 75C to 50C as well.

I had a scare when I tried to power the machine back on, and it wouldn't respond, so I had to take it apart again and reseat everything before it'd work. Don't like messing inside laptops; those little ribbon cables are too easily damaged...


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PostPosted: Thu Nov 15, 2007 1:25 pm 
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The worst part is the more the fans spin the more dust you get, its a vicious cycle.

I hate how quickly my Tuniq Tower gets dusty. Time to raise it up off the floor. At least I dont have to deal with fur balls.

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 Post subject:
PostPosted: Thu Nov 15, 2007 6:11 pm 
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Image

Not sure how this managed to build up! I don't really have this problem on my "proper" pc at home, since all the intakes are filtered and it doesn't seem to pick up much dust anyway.

Makes me wonder if anyone's selling a notebook with a dust filter you can pop in and out like a PC card... strikes me as a vaguely sensible idea if this is a common occurrence!


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PostPosted: Thu Nov 15, 2007 6:25 pm 
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Ummm, you said you were going to post pics of the fan from the laptop, not the clothe's dryer. :shock: :shock: :shock: :shock: :shock: :shock:


8)

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 Post subject:
PostPosted: Fri Nov 16, 2007 1:26 am 
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Wow.

Laptops are notorious for this. Probably because they draw air from so close to the desk.

Glad it's fixed for you.


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PostPosted: Fri Nov 16, 2007 3:24 am 
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Getting the temps back to sensible levels appears to have been worth about 150ppd, since it's not scaling down anymore.

I wonder if my battery life is likely to improve too, since the CPU, GPU and chipset are now running 30C cooler?


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PostPosted: Fri Nov 16, 2007 3:46 am 
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I'm the official part-time IT guy where I work. There's a room full of computers in a non-working state, which I've been working on. Virtually every one of them has an extreme dust build-up similar to the photo, but usually worse. Mostly it's a HD failure, probably caused by heat. I haven't found a bad CPU yet.....a tribute to the tough Intel P-4 chips.

The fix would be simple enough....a designed-in air filtration system, maybe with a software shut-down system that would require removing the filter for maintenance after a set number of usage hours.

Too simple I guess. The manufacturers would prefer you just bought a new computer every so often.

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PostPosted: Fri Nov 16, 2007 3:55 am 
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As a pointless aside, has anybody ever figured out why lint is always that pale blue colour? I'm guessing the popularity of denim...


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PostPosted: Sun Nov 18, 2007 10:28 am 
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I dunno, but it does burn quickly.


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 Post subject:
PostPosted: Sun Nov 18, 2007 12:18 pm 
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One more hint,

Do not live on the main street to a gravel pit! All the trucks going in and out give off a LOT of dust. I have to blow out my heatsinks about 5 times as often as I used to. Also, the content is obviously a lot more fine dirt particles here and a lot less lint than in this laptop.


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 Post subject:
PostPosted: Sun Nov 18, 2007 12:44 pm 
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Or just get rid of the cat. :shock:

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 Post subject:
PostPosted: Sun Nov 18, 2007 12:47 pm 
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soma wrote:
Wow.

Laptops are notorious for this. Probably because they draw air from so close to the desk.

Glad it's fixed for you.

Anything that draws air from close to the floor also has this problem, hence the need to raise towers or have them get air from someplace other than the bottom of the base.

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 Post subject:
PostPosted: Tue Dec 25, 2007 10:57 pm 
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aristide1 wrote:
Or just get rid of the cat. :shock:


Or better yet, just spend some quality time with kitty.... and a brush, every once in a while! :D

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PostPosted: Wed Dec 26, 2007 3:02 am 
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As to exactly where the dust comes from.....it's from the air, it's in the air. The location of the computer is secondary to the quality of the air. Also keep in mind that a tower computer sitting on the floor next to your desk, is going to sound much quieter than if were sitting on the desk. And an intake on the bottom of the case usually is quieter than an intake on the front of the case. This is SPCR....we are dedicated first to silence.

If the air in the room is dusty, with lots of foot traffic, pets, dirty carpets, etc, your computer without any filters will get just as dirty sitting anywhere. The idea is to keep everything as clean as possible.

Of course there are little dust/lint producers walking or flying around your house...your pets. This is where a built-in air filtration system directly on the computer is valuable. It's the very last barrier to dust entry for your computer......and it might be the only barrier in a dusty house with pets. Place your computer anywhere you want, but clean the air entering it.

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