I must run intensive applications on a laptop, which causes it to get rather hot. So I'm exploring cooling options.
One that I considered was to simply raise the entire laptop off the table (like a cooling pad would do), with something at the corners propping it up. However, I can envision a potential problem.
If it's merely suspended in the air, with very little air movement, it seems like this might be worse than sitting on a table. My reasoning is that air is not a good conductor of heat. When resting on a table, it can disperse heat INTO the table. When suspended, however, the air under it would get hot. Hot air rises, so it seems like some of the air would put heat back into the bottom of the laptop.
Those are the mental gymnastics behind my wondering whether the laptop would be cooler if I rest it on the table (MDF type), or raise it a little off the surface. My actual question is which option would be better, although it would also be great if someone could shed some light on why either is the correct answer.
p.s. I don't want to have to do this, but would turning up the fan speed a lot be a good idea?
Best Answer
This is a little like the bumble bee -- if it knew about aerodynamics it couldn't fly. You may be over-thinking this a little. Laptops are designed to be used. They include everything necessary to dissipate heat as long as you let them do the job. You should be able to set it on any solid surface, with some clearance so no vents are blocked, and do anything the laptop was designed to do.
This assumes you're using it in a typical work area that is at a temperature comfortable for people. If you're working in an unusually hot environment, you could think about augmenting its cooling ability.
The most important thing is keeping the the internal air flow good. That includes periodically cleaning out the vents, and getting dust off heat sinks and fans. If you use it in a dusty environment, you will need to do that more often than if it's used in a clean-room.
If the bottom of the laptop is solid
If the bottom of the laptop is solid and plastic, the surface material it sits on should make virtually no difference. Setting it on a laptop cooler would not affect much either. Raising it off the desk won't do anything but potentially make it unstable or stress the case.
If it has a metal case that's designed as part of the heat dissipation system, a laptop cooler or a solid metal desk would have little direct effect on instantaneous temperatures of the heat-sensitive components. However, they might, theoretically, provide a little extra margin if it runs hot for long periods (in the category of "shouldn't be necessary but couldn't hurt").
If the bottom of the laptop is vented
If the bottom of the laptop has air vents, the case should already be designed with the clearances it needs as long as it rests on a hard surface. There will typically be feet to provide some air flow space underneath. The surface material of the desk will make virtually no difference.
If there is an internal fan that exhausts out the bottom, raising it a little may make the fan more efficient. In this case, you would not want to put a cooling unit under it, since that would interfere with the fan.
If the bottom has only intake vents, raising it another fraction of an inch or using a cooling unit that blows toward the laptop "shouldn't be necessary but couldn't hurt".
The science explanation
I don't want to get too far off-topic for the site, but the gist of your heat question is this. If you were talking about a metal desk, the metal would conduct a lot of the heat away. A material like wood or MDF is an insulator, so not much heat will be dispersed. If you're comparing dead, trapped air to an MDF desktop, the affect of either insulator wouldn't make much difference to the laptop. If the air isn't trapped, there will be some turnover; if not a laptop fan pulling or pushing the air, then just thermal action and environmental motion. So an air gap would probably be theoretically better than MDF, even if the laptop has a solid bottom, although there might be no practical difference.
The trapped heat won't transfer back into the laptop, it just represents laptop heat that isn't being dissipated from the bottom surface. Just like if you bake food in an oven, the food will absorb heat from the oven. But it can't get hotter than the oven so that the food is heating the oven. Eventually, the food will reach the oven's temperature and the oven won't transfer any more of its heat to it.
All that aside, remember that the laptop was designed to operate in this way. It has either a solid bottom that is designed to sit on an insulating solid surface, or a vented bottom that contains provisions to ensure a gap for air flow. So the laptop case is already doing the heavy lifting on its own. It isn't so much a question of which option is better, as will either option make any difference?