Thermal Paste question

[Retro_X]

Hi

I was just wondering if someone could possibly tell me the proper way to apply thermal paste to a CPU. I have Arctic Silver, and I've been shown (a while go) to cover most of the CPU with a thin layer. I've been hearing that you can just add a dab or so in the middle and the heatsink will spread it for you.

So what I did is cover most of the surface on my AMD 64 X2 4200+, I have a Zalman CNPS9500-LED and the temps are usually between 35C and 38C idle. Sometimes 40C on a nice warm day.

So the way I applied the thermal paste was correct? I want to start overclocking, so I want to make 100% sure it'll be okay.

Thanks

 

[MJCfromCT]

Hi Retro,

Yes, you want as thin a layer of thermal paste as possible. Thermal paste has a very low thermal conductivity compared to the metal of the heatsink and the processor itself, so you want as thin a layer as possible to minimize the amount of thermal resistance and maximize your heat transfer from the CPU to the heatsink. Of course, you want a layer that is able to cover the entire surface of the chip, you don't want any air gaps between the heatsink and the CPU. Even though the thermal conductivity of thermal paste is low, it is immensely higher than that of the air that will exist in these gaps.

I'd say that covering it with a thin layer would be the way to go. Putting a dab of thermal paste in the middle of the CPU and hoping the heatsink will evenly push it around seems a bit unrealistic to me. You'd probably end up with an area in the center that had a thicker amount of thermal paste compared to the edges. You also wouldn't be sure if you got rid of any/all air gaps between the heatsink and CPU.

 

[pstang]

I'd say that covering it with a thin layer would be the way to go. Putting a dab of thermal paste in the middle of the CPU and hoping the heatsink will evenly push it around seems a bit unrealistic to me. You'd probably end up with an area in the center that had a thicker amount of thermal paste compared to the edges.

I dont think it matters too much either way, but if you think about it where is the core of the processor located... in the center, where is the compound going to be most effective... in the center.

On an Intel P4 or Athlon64 type CPU with a large metal heat spreader, put a small amount of Arctic Silver onto the center of the heat spreader as shown in the photo.

Only a small amount of Arctic Silver is needed

P4- About the size of an uncooked grain of short-grain white rice or 1/2 of a BB.

Athlon64- About the size of one and a half uncooked grains of short-grain white rice or 3/4 of a BB.
Our testing has shown that this method minimizes the possibility of air bubbles and voids in the thermal interface between the heat spreader and the heatsink. Since the vast majority of the heat from the core travels directly through the heat spreader, it is more important to have a good interface directly above the actual CPU core than it is to have the heat spreader covered with compound from corner to corner.

 

[Arcygenical]

Eh, I've used both methods and, well, to be honest there was no difference between the two. For ease of use, however, I purchased some of the zalman brush-on stuff... and it lowered my temperatures too.

 

[MJCfromCT]

I dont think it matters too much either way, but if you think about it where is the core of the processor located... in the center, where is the compound going to be most effective... in the center.

Yes, you are right, you want the compound to effectively transfer heat away from the core to the heatsink. However, that spreader is there for a reason, and getting it covered with a thin layer of thermal paste, as long as it is making good contact with the heatsink, will do nothing but help, even if the majority of the heat travels straight up and won't conduct out away from the core. Slightly more surface area the heat is traveling through = slightly cooler temperatures.

Putting a bead of thermal paste on the center of the spreader and hoping the heatsink will spread it around could leave you with a layer of thermal paste much thicker than desired, and also has you running the risk of leaving air gaps.

 

[Arcygenical]

Remember that the specification for mounting a s939 processor is up to 25lbs. When that paste get's warm, with 25lbs of pressure over top of it... it thins out very nicely. Try warming that stuff up in your hands (let alone 40'c in a processor) and see how evenly it'll spread with a plastic baggy.

The point of the IHS is not to spread heat. That's marketing bullsh*t. Cores were capped simply to prevent chipping and breakage... Something that enthusiasts (who were often manufacturing their own waterblocks and heatsinks on their own) desperately wanted.

 

[Retro_X]

Thanks guys

I basically just placed a dab in the middle and spread it out with this thing plastic 'thing' that came with an older heatsink and fan.

So those temps (38C), measured with Core Temperature, are okay for the X2 4200+?

 

[sparks]

go with what they paste on there how to on the site.

ceramic instructions
take a little on the sink and cpu rub it in circular on both services then try to wipe it off
with a lint less cloth....OR a coffee filter
then put a dab the size of a grain of wild rice (even half of what you think) in
the middle of the cpu...bolt down the cooler.

sparks

 

[ninty]

I put AS5 on both my 3500+ and x800 and all i did was put a small bead in the center and place the heatsink ontop. It works fine.

 

[Arcygenical]

Exactly. As I said, I've tried both methods... In the same setup and neither produced better temperatures.