why is my cpu overheating?

DiscoZombie

pre-edit: okay, it look like what happened is the heatsink came unseated. I think I failed at securing it properly. gg. my new question is, what do I do now? my heatsink and processor have some dried and crusty thermal compound caked on the area where they're supposed to be touching. Can I just snap the heatsink back on and hope for the best? do I need to clean both things and put on some fresh thermal paste (which I don't own and would have to go out and buy)?


So, what are possible causes for CPU overheating? At least I think that's what's going on. I wasn't doing anything CPU intensive - just surfing the net. All of a sudden my PC turns off. This had happened once before and never happened again so I hoped it was just a fluke. This time though, when I turned it back on, it turned off again shortly. OK, so this time when I turned it back on, I went into the BIOS and checked the CPU temp. Hmm, 89 degrees celcius... okayy why are you so hot when I wasn't even doing anything special? I let it sit for a few minutes, I opened up the case, and turned it back on. The CPU fan is running just fine. Went back into the BIOS, checked the temp again, it had cooled down to like 60 degrees, but rose rapidly, like a degree every couple seconds, until it was in the 80's again. whyyyyyyy?

This is a newish machine. Maybe a couple months old. First one I've ever built myself, and I was impressed that I got it to work on my first try. It ran perfectly for weeks, but now this - so much for my beginners' luck...

here are my specs. only thing different is that I realized I'd selected triple channel RAM when my CPU/mobo were designed for dual channel, so I got dual channel instead.
<img src="http://dl.dropbox.com/u/99279/New%20PC.jpg" border="0" class="linked-image" />

Thaldarin

Check your placement and thermal pastage.

spellman23

<!--quoteo(post=1774963:date=Jun 15 2010, 04:12 PM:name=DiscoZombie)--><div class='quotetop'>QUOTE (DiscoZombie @ Jun 15 2010, 04:12 PM) <a href="index.php?act=findpost&pid=1774963"><{POST_SNAPBACK}></a></div><div class='quotemain'><!--quotec-->my new question is, what do I do now? my heatsink and processor have some dried and crusty thermal compound caked on the area where they're supposed to be touching. Can I just snap the heatsink back on and hope for the best? do I need to clean both things and put on some fresh thermal paste (which I don't own and would have to go out and buy)?<!--QuoteEnd--></div><!--QuoteEEnd-->

No. You could try, but there's high chances of air bubbles (i.e. almost 100%), and air bubbles don't conduct heat, and thus you probably will overheat/fry the CPU.

The correct thing to do is purchase (or borrow) some thermal paste. Remove the existing thermal paste using rubbing alcohol just in case. Apply a little and rub it in to prime the surfaces, then dab about a rice kernel on the CPU and mount the heatsink+fan. Note that thermal paste doesn't conduct as well as metal, so to much = thick layer = fail.

DiscoZombie

yeah, sounds like I better get some thermal grease. Maybe I can borrow or buy some from the IT dept at work. I blame Intel for my failure! I followed their illustrated instructions for securing the heatsink exactly, down to the last page, which showed that you had to turn the 4 screws a quarter turn to tighten them. Well, it turns out that last page wasn't really the last page, it was the first page of how to REMOVE the heatsink... so i had snapped it into place, and then immediately loosened it for removal -_- fail. now I'm stuck typing on this awful old computer with a wireless keyboard that misses keystrokes.

Cereal_KillR

How did you put on your heatsink? Did you use the thermal pad that comes with some generic heatsinks? In fact, are you using the stock heatsink?

Note that the drying/crusting/melting effect is very normal. What thermal compounds do is to fill the microscopic holes and grooves due to imperfect machining (perfect machining is near-impossible to do, especially on a commercial scale). The melting happens when the CPU heats up, and sets the thermal compound into place.
Ideally, optimal heat transfer happens when the two surfaces, the heatspreader and heatsink, are perfectly complementary (perfect fit, usually two perfect planes). Perfection isn't possible, and the holes results in air trapped between the two metals. Air is a poor heat conductor.
The role of the thermal compound is thus to fill these holes, as it has better thermal conductivity than air. But it has less thermal conductivity than metal. So you're supposed to put as little thermal paste as possible, to fill the holes, but to allow the metals to keep in contact.

tldr version is: No thermal paste is better than too much thermal paste. Also, any time you remove the heatsink, you have to clean it and re-apply new paste.

DiscoZombie

thanks - and yep, just using the stock heatsink with stock thermal pad that came with the processor. I don't intend to overclock or anything as I doubt it would give me a tangible performance boost, so I'm happy with stock. hopefully I can get my hands on some more thermal paste tomorrow. I drive an hour to work through the suburbs and I don't pass a single computer store =/

spellman23

<!--quoteo(post=1774990:date=Jun 15 2010, 06:17 PM:name=Cereal_KillR)--><div class='quotetop'>QUOTE (Cereal_KillR @ Jun 15 2010, 06:17 PM) <a href="index.php?act=findpost&pid=1774990"><{POST_SNAPBACK}></a></div><div class='quotemain'><!--quotec-->tldr version is: No thermal paste is better than too much thermal paste.<!--QuoteEnd--></div><!--QuoteEEnd-->

For sufficiently large amounts of thermal paste.

Scythe

Anecdote: My video card always ran super hot (100C under load, HD4870X2). I decided to clean it the other day, this involved removing the whole heatsink and fan arrangement from the side of the card to get at the dusty bits. After evacuating about a cubic metre of dust, applying the very last of my thermal paste (arctic silver), reassembling everything (Attaching the shroud with duct tape instead of twelve or so tiny screws), I fired it up to find a 20 degree decrease in operating temps. The old, dry, cracked crappy stock heat goo was awful.

Moral of the story: Stock heat conductive goo is crap.

--Scythe--

Thaldarin

I'd buy a non-stock heatsink for your CPU too.

I'd suggest something like this: <a href="http://www.newegg.com/Product/Product.aspx?Item=N82E16835608018" target="_blank">http://www.newegg.com/Product/Product.aspx...N82E16835608018</a> But browse yourself.

Spooge

As long as you aren't overclocking, the stock heatsink should be fine. The 4 post design that Intel uses totally sucks to install when compared to AMD's clamp. Here's a tip: when installing the heatsink, place the motherboard on a diagonal over the open motherboard box. Installing it this way gives you more leverage and better visibility than if you try to install it inside the tower.

That_Annoying_Kid

mmmm

artic silver

my buddy has one of these in his computer, <a href="http://img.hexus.net/v2/internationalevents/computex2007/TS/Wed/IMG_5143-big.jpg" target="_blank">http://img.hexus.net/v2/internationalevent...MG_5143-big.jpg</a>

I think it's slight overkill

spellman23

<!--quoteo(post=1775041:date=Jun 16 2010, 03:05 AM:name=Scythe)--><div class='quotetop'>QUOTE (Scythe @ Jun 16 2010, 03:05 AM) <a href="index.php?act=findpost&pid=1775041"><{POST_SNAPBACK}></a></div><div class='quotemain'><!--quotec-->Moral of the story: Stock heat conductive goo is crap.

--Scythe--<!--QuoteEnd--></div><!--QuoteEEnd-->

Not 100% true, but usually the stock amount applied is way too much and thus you don't get a tight thin layer of the stuff.

The stock heatsink/fan for CPUs are fine as long as you don't overclock. I actually typically replace the paste, and my current build has a beefed up heatsink/fan.

Also, for Scythe, I wouldn't be surprised if the dust had a huge part to play in the overheating. Dust = insulation = no heat leaving.

DiscoZombie

thanks for the tips peeps. went to Radio Shack and got some arctic silver and now I'm up and running again. I knew radio shack had to be good for something! I think I'll stick with a stock heatsink unless heat remains a problem or until I feel like I need moar power - but if I wanted more CPU power I probably would have just gotten an i7 instead of an i5 to begin with =p I splurged on video and skimped on cpu

Xyth

On a somewhat related note, I was fixing a siblings computer and had to detach the heatsink to clean it out. Note: This computer was bought off ebay.
Upon removing the heatsink I found that whoever originally built it took the CPU temperature probe (hooks up to the front bezel for temp monitoring) and decided the ideal placement would be in the thermal paste between the CPU and heatsink. This effectively destroyed the thermal conductivity between the two. These things are supposed to be mounted under the CPU or close to it on the heatsink. No wonder this box has been suffering heat problems since it was bought.
Seriously, I was shocked to see this when I took it apart. Needed to share it with someone else.

Thaldarin

Stock heatsinks are terrible. Toms Hardware, Guru3D, go read reviews on heatsinks/fans and they will show you just how big a difference it makes. Especially gaming and under load.

lolfighter

That depends on which stock heatsink we're talking about. And keep in mind that stock heatsinks are usually intended for stock clock speeds and voltages. For instance, the heat sink that Intel ships with their Core2 processors is entirely adequate provided you don't overclock your CPU, don't overvolt your CPU, and don't run it inside a cabinet with poor airflow. And that's even with the stock thermal paste, too. I've heard several stories about people who managed to overclock their Q6600 with the stock cooler with no heat issues at all simply by applying some better thermal paste.

For reference, my E8400 (not overclocked, not overvolted, stock heatsink, stock thermal paste, reasonably good airflow) never goes above 55C during normal use, with Prime95 being able to reach 60C. For the E8400, safe temp is 65, warm is 70, hot is 75.

Talesin

Stock heatsinks will keep a CPU within the operating ranges it's designed for, within reason. Problem is, the amount of temperature cycling produced (even within tolerances) WILL shorten processor lifespan. So even if you aren't planning to overclock, a better cooling system IS a worthwhile investment... $60 more to keep your system trouble-free, with a comfortable, CONSTANT margin on the thermal front means years of additional service, assuming proper maintenance and cleaning is done is quite 'worth it' to me.

PS- I use that Coolermaster on my old Ath64 3200+ box. Still running like a champ. :D Early adopter FTW.

Pstrangler

<!--quoteo(post=1775041:date=Jun 16 2010, 06:05 AM:name=Scythe)--><div class='quotetop'>QUOTE (Scythe @ Jun 16 2010, 06:05 AM) <a href="index.php?act=findpost&pid=1775041"><{POST_SNAPBACK}></a></div><div class='quotemain'><!--quotec-->My video card always ran super hot (100C under load, HD4870X2). I decided to clean it the other day, this involved removing the whole heatsink and fan arrangement from the side of the card to get at the dusty bits. After evacuating about a cubic metre of dust, applying the very last of my thermal paste (arctic silver), reassembling everything (Attaching the shroud with duct tape instead of twelve or so tiny screws), I fired it up to find a 20 degree decrease in operating temps. The old, dry, cracked crappy stock heat goo was awful.

Moral of the story: Stock heat conductive goo is crap.

--Scythe--<!--QuoteEnd--></div><!--QuoteEEnd-->

Same kind of thing happened to me, I couldnt get to play games for more than 30 mins before my GPU ran over 100C (Asus GEforce 7950GT). One day I went out and bought a Zalman cooler and some artic silver 5 paste.
The GPU then ran around 40c at idle and below 55C any time under load.

I since then replaced the card with a 4870 (also from ASUS) so far the stock thermal paste is ok, I never saw it rise above 60C.

As for stock coolers, if you don't OC they should work ok, I have a Core 2 'slightly' overclocked (I pumped from 266 to 272 which results in 2450GHz instead of 2400) and it runs fine on Stock cooler, I admit I applied some Artic Silver though to replace the stock pad (which would be very old now anyway. CPU runs cooler too now with AS even if it is now overclocked.