# what is the role of paste used below the processor?



## dittualex (Nov 17, 2005)

hi,
i want to know Y we are using the paste below the processor


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## geekysage (Nov 17, 2005)

To give you a short-no-bs reason, the thermal paste between the cpu and the heatsink-fan (HSF) is used to better the heat transfer from cpu core to the heatsink. Every metal surface has tiny pores which may trap air and make the heat transfer slow. Now that may raise a question in your head, why would we wanna better the heat transfer? Well, that's a simple high-school science topic: The resistance of a metal increases with temperature. Hope that clarifies it for ya.

Now, if you still have some doubts, read this: *www.neoseeker.com/Hardware/faqs/kb/2,22.html


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## kalpik (Nov 17, 2005)

I think we want better heat transfer cause we want the maximum heat to be transferred to the heatsink so that it can dissipate it faster.


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## praka123 (Nov 18, 2005)

Thermal pads will be sufficient ?


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## siriusb (Nov 18, 2005)

Avoid thermal pads as much as possible. They can be used in low temp situations or as low-cost solution.


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## geekysage (Nov 18, 2005)

*@kalpik:* Did i say otherwise? Ofcourse, "...we want the maximum heat to be transferred to the heatsink so that it can dissipate it faster." But why do you want better heat dissipation? I answered that by saying, "Now that may raise a question in your head, why would we wanna better the heat transfer? Well, that's a simple high-school science topic: The resistance of a metal increases with temperature."  :roll: 

*@siriusb:* I agree.

Anybody looking for some good reading on Thermal Interface Material: Grease vs. Pads may refer to this amd document:

*www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/26951.pdf


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## praka123 (Nov 19, 2005)

So i need to apply thermal paste b/w HF and Processor(is a p4 2.8 HT prescott on 915 GAV intel original)which got a heating problem?what thermal paste will i use?(easy to get).can i reassemble the processor heatsinkfan combi?what should i do to clean the processor surface>?some people say we need to redo the thermal paste every year...?


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## geekysage (Nov 19, 2005)

*@prakash kerala:* Yes, you should use some thermal paste b/w the HSF and the cpu core. If you've a boxed CPU then it came with a thermal pad  already applied to the HSF so you prolly don't need to change it. Not really sure if it's available in India but i use Arctic Silver 5 thermal paste and it's worked great for me. Ask a local assembler and he could help you with it. You can re-assemble your HSF-CPU as long as you put new paste every time you put them apart. Changing the thermal paste every year is not a bad idea but is not necessarily needed unless your temps go really high.

Here's a step-by-step guide.


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## kalpik (Nov 19, 2005)

Im really sorry but u said "The resistance of a metal increases with temperature." What does that have to do with the processor?? How does the resistance of the processor or the heatsink matter?? I really didnt get that! Could you please explain in more detail?!

Thanks..


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## geekysage (Nov 19, 2005)

Alrite, there's a sorry, please AND a thanks thrown in there so i have to watch my mouth now.

Either you don't know s_hit about processors or for that matter, any hardware, or you are just acting dumb for some reason. Here's a link explaining how cpus are fabricated using metals and silicon. And here's a link explaining temperature affect on cpu.

If you still don't get it, here's the low-down:

High Temperature --> More resistance inside the cpu fabricated using metals and silicon -->= low conductivity --> slower signal (/data) transfer inside the cpu --> low performance

....to read this in a sentence, you can read "-->" as "gives rise to".

Since I did high-school as well as two years of engineering college physics, it would probably sound too complex if i go about explaining how the resistance of a metal increases with temperature. Nevertheless, here's a try:

a metal getting hot --> random electron motion inside the metal increases --> lower drift velocity of the electrons i.e. heat creates resistance --> lower conductivity

Here's some more:



> Q. How does a thin layer of silicon-28 with higher thermal conductivity affect the temperature in a microprocessor when the heat must diffuse through the bulk silicon wafer, which is much thicker?
> 
> A. Average temperature of the chip will probably not be affected. However, the very localized temperatures at the p/n junction of a transistor can be greatly affected. Different parts of an integrated circuit experience different operating conditions. The logic core of a microprocessor can be operating almost continuously, while the temporary storage areas are accessed less frequently. This leads to areas of the chip that generate more heat than other areas. These "hot spots" determine the maximum operating conditions of a circuit design. The higher conductivity silicon-28 layer spreads the heat from these active areas better than natural silicon, thus reducing the maximum temperatures.
> 
> ...



Peace.


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## kalpik (Nov 19, 2005)

Oh that i know! Even im a computer science engineer (B.Tech). Actually it was a misunderstanding on my part! Never mind.. Sorry 4 that dude! Chill!

Regards..


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## geekysage (Nov 21, 2005)

No probs, kalpik. *www.penthesilea.ch/yabb-smiley-sets/peace/wink.gif


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## wORm (Nov 21, 2005)

Brushing Teeth. No, not really.


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## mohit (Nov 21, 2005)

keep it simple guyz .. the thermal paste si used to run ur cpu cooler. dats it !! u dont need to go into all the physics involved


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## geekysage (Nov 21, 2005)

i know, man...i was just wondering how far a conversation can get dragged out of the picture.

*@wORm:* mwaahahaha...rite on! *geekysage.hostachio.com/rofl.gif


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## praka123 (Nov 21, 2005)

will i be void of my processor warranty(1 Yr old).if i reinstall my processor,removing HSF and put thermal paste?.is there any chances for damage of processor if i try to remove....sorry guys am very weak on H/W parts.... :dump:


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## mohit (Nov 21, 2005)

prakash kerala said:
			
		

> will i be void of my processor warranty(1 Yr old).if i reinstall my processor,removing HSF and put thermal paste?.is there any chances for damage of processor if i try to remove....sorry guys am very weak on H/W parts.... :dump:



if ur procc is not giving u any trouble dont simply try reinstalling it ..and if u havent done it before be very careful or rather get some expert help. the warranty becomes void if u induce any physical damage to the procc. so just be careful there.


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## praka123 (Nov 21, 2005)

Oh,I see i don wanna my procee(Intel) to goto Philippeens


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