cooling - What is this rubber pad under my laptop's heatsink?
2014-04
Alex Yan
I opened up my HP HDX laptop yesterday to clean it (Warranty was over 2 years ago), and to apply new thermal paste.
My laptop has only 1 fan, 2 sets of fins connected to 2 copper pieces to conduct heat. Around the graphics card, there are these really soft black rubber pieces stuck on the heatsink, and it makes contact with things like the memory modules of the graphics card, and some other parts. There's also this thicker light blue colored rubber piece between the northbridge and the heatsink.
The CPU and GPU chips use thermal paste, but I don't know what these rubber pieces do. Are they used as a substitute for thermal paste? There's a fairly large gap between the heatsink contacts and the chips without the rubber pieces so I figure that normal thermal paste won't work as well. There's no thermal paste between the rubber pieces and the parts it makes contact with. Would it be better to apply thermal paste to that?
GPU: 9600M GT overclocked when I play games, way underclocked when I'm not
CPU: Intel Core 2 Duo P7450 2.13 Ghz
GPU idle temp 49 C
CPU idle temp 39 C
Some people say these temps aren't high, but they are higher than when I bought the laptop (Also, currently in my area, humidex is around 35 - 42 C, around 27 - 30 C outside, 62% humidity. It's been so hot lately that some of my rubber bands melted into a sticky goop...)
Synetech
The rubber pads are shims that prevent the components from touching or grating and they provide a little, soft support like a pillow, so that the components are not hanging in the middle of the air but also without having them bolted down. This is especially important for moving components like fans and hard-drives since having them hard-bolted to the chassis would create a lot of vibration and noise; having them sit on rubber shims absorbs the vibrations, creating quieter laptops. They are also insulators that prevent potential short-circuits. Do not apply the thermal paste to the rubber shims!
Yes, those idle temperatures are good and yes, it will be hotter than when you first bought it because the laptop now has a bunch of dust inside it which not only prevents airflow as well as a clean system, but also actively warms the system like a blanket. Unfortunately a fan is insufficient to keep the dust out because dust is mostly dead human skin which usually has oil and other stuff that makes it sticky, so simply blowing it won’t make it go away; it has to be wiped away.
It should come as no surprise that the ambient temperature has a big effect on a computer’s temperature. It may seem like electronics are only concerned with the temperature reading on the thermometer, not the humidex since they don’t sweat, except that humidity does indeed affect them, so yes, 35-42°C is going to make a computer run hotter.
Journeyman Geek
Its probably thermally conductive tape - such as this 3m stuff. As far as hardware goes it has a few advantages - its less messy than classic thermal compound, in theory is removable, and probably is easier to mechanically attack than standard heat sink compound. It also acts as a adhesive, so these parts usually arn't screwed down.
Without modification, replacing it with thermal compund may not work very well, since there's nothing holding these parts in place.
Gregory MOUSSAT
Those "rubber" pads are not made from rubber. They are made from some eat conducting matter.
The goal is to replace replace thermal paste, because thermal paste only works if the surfaces are very flat.
With modern CPU, GPU and others, having a flat surface + thermal paste have a higher cost than irregular surface and rubber pad. The drawback of the rubber pad is it is less efficient to transmit eat to the eatsink (but it is worst with thermal paste + irregular surface).
Rule of thumb: never use/reuse a damaged rubber pad. Because the only advantage of a rubber pad is to stick to the entire surface in order to transmit the maximum eat. If it is damaged, less eat is transfered. So you have to flatted the surfaces (this is a long task) and apply thermal paste.
Gr-Tech
As mentioned above those "rubber" pads are thermal pads. When you remove the heatsink those pads should be replaced because after a while they get the shape of the GPU and when removed and placed back again it is imposible to fit perfectly again. There is a product called K5-PRO which is actually a very gummy thermal paste and can replace thermal pads of up to 3mm thik. You can find it on ebay for around 6$ here http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=261419411897
Tom
I have a laptop with a Core 2 Duo processor and the cooling fans are spinning most of the time. I'd say the computer is silent in 10% of the time and the fans are working in 90% of it.
I don't have any problems with performance, but I was wondering if employing a laptop pad could drastically cut down on the spinning of the internal fans. I like complete silence, so I'd buy a laptop pad if it could, for example, reverse the above ratio, so the computer would be silent in 90% of the time and the fans would spin only in 10%.
Is it a realistic expectation when using a good quality cooling pad?
CarlF
The cooling pad would be likely to reduce the fan-spinning, but with no air circulating in the tight spaces of a laptop, you can't expect the fans to stay off very long--that Intel chip is generating lots of heat (depending on which one you have, up to 35 watts) and all that energy has to go somewhere. The fans push it out of the case. Conduction with the cooling pad can't cool any part of the laptop except the very bottom, because there isn't room for air to circulate naturally.
phoebus
First, I assume you're referring to a pad with built-in fans, in which case those fans are going to be making noise anyway.
Second, external fans are nowhere near as thermodynamically efficient as internal ones where a laptop is concerned. If your system is already hot, you're not going to see a 90/10 -> 10/90 reversal.
If you're talking about a purely heat-conduction-based cooling pad, then this is even more the case, although obviously the first issue won't apply.
ioSamurai
Cooling pads are more for you and your legs than for the internals of the laptop. Unless the cooling from the pad is penetrating enough to lower the temperature sensors inside your computer then it's not going to change the speed of your internal fans.
The heat is originating inside the machine from the power supply or battery, and you're not likely going to offset this very much by applying cooling externally. If you are in a very hot area where the air is hot, cooling the air in the entire room will likely make more of a difference than applying a cooling pad.
The closest a cooling pad would come to making a difference would probably be on a model like the MacBook Pro or MacBook Air where the aluminium case is part of the heat dissipation design. Though even then you'll only be able to do so much to pull extra heat off of the metal faster.
As you can imagine, keeping the laptop on a surface such as legs or a bed or blanket will insulate the device causing air to not flow and increasing heat build up. As you can imagine even placing a solid surface between the laptop and the blanket will improve airflow and cooling, and a cooling pad could be useful here as well.
Journeyman Geek
You need to clean the dust accumulated on the laptop fan(internal). Open up the back of your laptop. Remove the fan(mostly found on the corners), and open internal parts of the fan if you can. You'll find a lot of dust in there. Blow it with a dryer, or use cotton+alcohol. you'll have to clean the air vents in the side of the laptop(looks like grid, its a heat sink). Once all the dust is gone your laptop's cooling system will work efficiently.