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Info regarding high temperatures, causes/solutions, and reading from the CPU diode

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@md0Cer

Senior Member
Joined
Nov 6, 2003
Location
Denver, CO
Info regarding high temperatures, causes/solutions, and reading from the CPU diode

Ok, I have seen many many threads with people freaking out from their temperatures. I feel like addressing the temperature issue once and for all so later I can just paste a link.

What diode are your reading? Your Socket? Bad. Your CPU's internal diode if you can? Good. A 3rd party diode that you bought yourself? Depends, but probably good.

Why? Well, the socket thermistor is probably the most inaccurate reading for your CPU temperature. Your CPU diode is probably the best you can get but still not that great because motherboard manufactures alter the readings sometimes.

When a company like AMD for example says the CPU's maximum guaranteed continuous operating temperature is 85°C, that is not 85°C on the socket...it is on the CPU diode that is included in the chip!

Now, on to maximum temperatures......

If you are reading from the CPU diode, a 50°C temp will not kill you. It will not kill your CPU. It will not burn your house down. It will not create a nuclear meltdown. Your skin can most likely handle 50°C. You may get a slight slight slight burn....

Now...yes...some motherboard manufactures alter this reading, so let's put the "just to be on the safe side" line at 60°C. If you are doing extreme voltages I recommend lower.

Will the CPU instantly be a goner the split second it crosses from 84.9°C to 85°C? No. That recommendation your CPU manufacture says is the "Maximum Temperature" is what is really the highest temperature that they will guarantee the CPU will be STABLE, with no damage, for continuous operation.

I personally have ran constantly in the low to mid 80's on my AMD 1700 for about a year now. I finally got some great cooling and am doing the low to mid 50's with an SLK-900 and 160CFM of rated air moving through it. Is it less stable from running in the 80's so long? Nope....

I think it is appropriate to share the story of when my heatsink was not seated right and I smelled my crappy thermal compound start to burn a little, and that sticker start to darken. Still works fine...100% load while folding...

My fan once died too, my last MBM "every 30 seconds" log was in the 120's.
Still works fine to this day..... Really, nasty things only happen when you go above 120°C for a brief time.

BTW, when I was running in the 80's my socket temperature read in the 50's...that goes to show you, you shouldn't trust it.

The bottom line is...your temperatures are most likely better than you think.

To be on the safe side, I would keep the Socket temperature under 60°C, preferable under 55°C IF YOU CANNOT READ THE CPU DIODE.

If you can read the diode, I would stay under 70°C to be safe. For overclocking, remember, lower temps help stability, at 80C I was doing 2.4ish GHz at 1.875Vcore, now I am doing in the 2.5's with that same vcore and my temps in the 50's.

I hope this comforts some people.

BTW, just for the information I have seen 2-3 other people who most likely share my view, and my information is based off of my own experiences, and the experiences of many others in this forum that I have been reading every day for almost 2 years.
 
*WORK IN PROGRESS*


HOW TO LOWER TEMPERATURES

http://www.overclockers.com/tips1179/ >>>A cooling article by batboy.

http://www.ocforums.com/showthread.php?t=298736 >>> A dual fan duct howto by me. I might add pics in a few weeks :)

http://www.ocforums.com/showthread.php?t=276042 >>> Lapping a bare CPU core

http://overclockers.com/tips1015/ >>> Lapping a heatsink article

http://www.overclockers.com/tips1087/ >>> Removing the heatspreader. BTW, do not do this with a Prescott as it is now soldered to the core and you will rop your core out. Ask in the apropriet CPU forum, Intel, AMD, general CPU's (if it isn't an AMD or Intel), before trying to remove your heatspreader.
I will add more articles as I see them :)
 
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*WORK IN PROGRESS*


CAUSES FOR HIGH CPU TEMPERATURES (and solutions!)

Heatsink Seated Improperly
It could be that your heatsink is seated improperly. If so, your idle temperature on your CPU diode will be high, and your load temperature will be even higher and by a good 10+ degrees and rise instantly (roughly in the blink of an eye type of "instantly" ). How to solve this would be:

  • Take heatsink off
  • Clean off CPU and bottom of heatsink with 91 percent Isopropyl Alchohol
  • Apply some silver sompound to the heatsink, rub it in and then off,this is rumored to fill the microscopic cracks and stuff in the heatsink.
  • Apply a thin layer to the CPU core or heat spreader, make it even but thin as possible..not too thin..but thin.
  • Make sure you don't get any dirt or anything in!
  • Carefully put the heatsink back on

Heatsink and/or CPU heatspreader not flat!
If your heatsink and/or cpu heatspreader is not flat, you will see high temperatures and a large gap between load and idle temperatures on your CPU core. How do I fix this?

  • Take heatsink off, take CPU out if lapping the heat spreader.
  • Find a perfectly flat block, or surface.
  • Get some sandpaper, from 400-1000 grit (you can find these high grit count sandpapers at autoparts stores)
  • Place the sand paper on the flat surface, hold the heatsink or CPU surface on the sand paper, and rub it. Make sure it is flat. Your goal is to get them perfectly flat.
  • Start sanding with the lower grit, like the 400. Remember, your goal is to get it perfectly flat, so make sure you are not tilting anything, and make sure the sand paper is perfectly flat against the surface, or against your perfectly flat sanding block (none that I know of unless you take something that is glass and really flat or like a thing of polished granite. You can sand in any direction, it does not matter as long as it is flat, if it is diagonal, horizontal, vertical, or circular. If I do something that is not circular I do it in the opposite direction, like vertical after going horizontal so the small scratches are not all the same direction, and thus it could be smoother and more flat.
  • Look so see after a few seconds if the scratch marks from the sandpaper cover all of the surface, just the middle, or just the outsides. When it does not cover a certain area...that means it is not flat. Keep going until it is flat, then move up gradually to the 1000 grit.
  • Clean off CPU and bottom of heatsink with 91 percent Isopropyl Alchohol
  • Apply some silver sompound to the heatsink, rub it in and then off,this is rumored to fill the microscopic cracks and stuff in the heatsink.
  • Apply a thin layer to the CPU core or heat spreader, make it even but thin as possible..not too thin..but thin.
  • Make sure you don't get any dirt or anything in!
  • Carefully put the heatsink back on

Look at my post above for some lapping links :)

Thermal Paste/Grease too thick!
One of the most common causes for high temperatures is putting on a layer of thermal compound that is too thick. It depends on how flat your heatsink is. If you have a horribly unflat heatsink, maybe a thicker layer would be required for it to make contact. Usually a thin layer is better. You still want to be able to see thermal compound on there, but make it as thin as possible. Sometimes a good way to tell is if there are numbers or letter on the core or heatspreader. If you are just about to the point of being able to see the numbers, but just a wee bit thicker. That is usually ideal, and is quite thin.

  • Clean off heatsink and CPU with 90% Isopropyl Alchohol, or that Arctic Silver cleaning thing. If you have to use 70 something % Isopropyl Alchohol (rubbing), it should work ok. Use a lint free cloth or paper towel that does not leave anything behind.
  • Rub some of the compound into the heatsink before starting, just a little bit, enough to fill the microcopic cracks. Could just be a myth, but I do it.
  • Apply just a little bit to the CPU core or heatspreader, just a little, you can always add more.
  • Put on a glove or put your finger in a bag and rub it so it covers the whole core or heatspeader. If too much is on, just wipe off your bag or glove covering your finger with a paper towel and spread it around. Remember, have a thin and consistent layer, but not too thin.
  • Attach the heatsink! Don't let it sit around exposed for a long time, you don't want dirt on it, or cat hair, etc.


Dust/Dirt

Many heatsinks over time, between 3 and 10 months will get clogged with stuff like dust, cat hair, etc. Not only does this reduce the amount of airflow that can flow through the heatsink, but it also acts like the heatsink just put on a warm winter coat. Now, we wouldn't want that as we are trying to cool down the heatsink, not insulate it and warm it up.

  • Take the heatsink off and wipe off the thermal compound.
  • Take a high powered vacume, and suck the dust out. This is not nearly as effective as blasting the living **** out of it with a waterpik. A hose with a pretty high powered nozzle or even just your own hand as the nozzle will work pretty good.
  • Once all that stuff is blasted out, it is usually good to dry it pretty quickly so it does not oxidize, or rust, or whatever. I use a hair dryer on high. It usually blows the water out. At first I hit the cool shot button as that works best as you don't really need the heat. Once all the water droplets are blasted out, then maybe apply heat to evaporate anything you might have missed. (Inside the core thingy on the base of my SLK-900 I am not so sure if any air blew the water out of that). Watch out, your heatsink does a better job at disipating heat throughout itself that you think and you can easily burn your fingers within a few seconds of this.
  • Just like stated previousely you will have to re-apply thermal compound and clean it, etc. to put the heatsink back on.


More to come :)
 
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*WORK IN PROGRESS*

KEY:
*unconfirmed


WHAT CPU's HAVE A DIODE


AMD
<Socket 462> Duron/Sempron/Athlon XP with Palomino, Thouroughbred A and B, Barton, Thornton, and Applebred cores.
<Socket 754/939/940> All CPU's compatible with these sockets (Sempron, Athlon 64, Athlon FX, and Opteron).

Intel
<Socket 370>All
<Socket 478>All
<Socket 775>All


WHAT MOTHERBOARDS CAN READ THE CPU DIODE

AMD
<Socket 462> Asus A7N8X, all Abit KT-400 (Abit KD7 for sure) or newer Via based boards*, Chaintech Zenith Ultra 400, Soltek FRN2, all Soltek Nforce 2 boards*, anything else. *
<754/939/940>
Intel
<Socket 370>
<Socket 478>All Abit boards
<Socket 775>



WHAT MOTHERBOARDS CAN'T READ THE CPU DIODE

AMD
<Socket 462> Abit Nforce boards and all Via KT133 and KT266 based boards.
<Socket 754/939/940>
Intel
<Socket 370>
<Socket 478>
<Socket 775>



***So far thanks to these people for this information:
  • David
  • nikhsub1
  • Wicked_Klown
  • Susquehannock
  • NookieN

Want to be added to the list? Tell me if your board can or cannot read the CPU diode temp! (Only if your board is not listed, or is listed with a "*" on it.)
 
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Setting up MBM5

1.) Go to http://mbm.livewiredev.com

2.) Download the latest version of MBM5

3.) When installing, you will be presented with a large list of motherboard manufactures and their models. Select yours. MBM5 is not under development any longer so your motherboard may not be listed. If not, see the post below this one. (coming soon hopefully)

4.) under the temperatures tab, look for diodes named LM-something usually LM-84 or LM-90. These are most likely the CPU core diode inside your CPU that I have much talked about in the first post of this thread.

5.) Select that as your "CPU" temp.

6.) See if it really is. Select the others and list them as 1,2,3,4 etc. Then look at whatever one is the highest reading. This is most likely your CPU diode. If you look in your BIOS, you should see it labeled, you should have two CPU ones, and one system. The highest CPU reading is your diode. Then go into MBM and look for the one that reads the roughly the same reading. This will be the same thing as in the BIOS. **Note, your system should be idling as it idles when in the BIOS, that means no DC programs, no load. Also notice the fact that a CPU diode will jump INSTANTLY 5-10 degrees C when you change from idle to load and the others will slowly follow. That is another trick to knowing which one is your diode.

Good luck, if you have any questions, ask away :)
 
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Interesting article... might need to see if we can get this stuck ;)
 
@md0Cer said:
What diode are your reading? Your Socket? Bad. Your CPU's internal diode if you can? Good. A 3rd party diode that you bought yourself? Depends, but probably good.

Why? Well, the socket thermistor is probably the most inaccurate reading for your CPU temperature. Your CPU diode is probably the best you can get but still not that great because motherboard manufactures alter the readings sometimes.

Could you (or someone) tell us how to figure out if we can read of the diode? Then people with different motherboards could come here and a database could be created of motherboards that read from the diode and those that cant.
 
upstreamcurrent said:
Could you (or someone) tell us how to figure out if we can read of the diode? Then people with different motherboards could come here and a database could be created of motherboards that read from the diode and those that cant.


Well, AFAIK Thunderbird based Athlons and Spitfire based Durons didnt have a diode so KT133 based boards (and KT133A, KT266, KT266A) based boards didnt read from diode, but from the Socket.

AthlonXPs (Palomino, Thoroughbred, Thornton and Barton) come with diodes, so I would imagine boards designed with these CPUs in mind will read from the diode.

One way to check is to look into the socket. On my old KT133 Jetway board from years past (I sound like an old fogey) there was a small sensor visible, on two stalks attached to the PCB. On my K7D, they arent there.
 
holy hot damn! I didn't think this would be stuck yet.

Anyways, I am sorry, I am on a Dell this week and do not have access to MBM yet. I should be posting some info soon. Unfortunatly...my rig isnt connected to the internet...so what I would have to do is write it down and post from school, that is what I usually do. Allot of info, plus info on how to read, and reduce temperatures should be on the way. In the mean time...I have another site to revive, and I have to revive the Folding Mentor Project, then I can revive this thread.

Hmm...everything I run seems to get a heart attack...I must get in over my head. Don't worry though...stuff coming soon.
 
agree wholeheartedly. people are incredibly upitty if they are in the 40s when hugely overclocked. lots of useful information, that most people only learn when the encounter a problem. With a little work this could be a sticky
 
Ok, just for info's sake, I am being a mean CPU nazi and telling good members like dicecca112, and deathman20 to move their posts to the end of the thread so I can have a bunch in a row to post info. Also Leviathan41 volunteered to move his, but I think he just deleted it. Oh well. Anyways, :clap: for them! :thup: Thanks guys.
 
I have to agree with this. If it runs, its stable, and its below the manufactures max running temperature, then its fine. Yes cooler is always better but its not like the CPU will jump up and run to the nearest body of water if its running hot for a period of time.

Good post, and good read for people who are concerned

(Moved from the top of the post by request)
 
dicecca112 said:
agree wholeheartedly. people are incredibly upitty if they are in the 40s when hugely overclocked. lots of useful information, that most people only learn when the encounter a problem. With a little work this could be a sticky

Thanks. It is a real work in progress. I just have no clue what to do for my school essay thingy so I am stopping in and adding stuff to this every now and then.
 
Lots of excellent information here (and crazy stories about incredibly high temps, lol). I deleted my last post a while back to give more flow to this thread, and just wanted to say nice work on this. :thup:
 
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