Computer Cooling

[SARGE]

Help me understand something here. Ambient temp is the temp in a room, right? So say your room is 78 degrees (F). If you have fans sucking in air into your PC, they are blowing in 78 degrees of air onto your components, right? So if your mobo, ram, cpu, video card would prefer it to be 70 and you're blowing 78 degrees, you're actually going downhill in cooling. On the other hand if your monitoring stuff shows something running at say 85 degrees (F), you can help it by blowing in the ambient 78, correct? I know if it's hot for you and you have a fan blowing it "feels" good because it does. Our PC stuff don't sweat or feel.

[David M]

Electronics don't prefer a temperature in particular, they just run more efficiently the cooler they are. There are of course maximum temperatures where exceeding it can cause damage. As temperature increases so does the electrical resistance through conductors and semi-conductors.

Part of reason we feel cooler when a breeze blows is from the evaporative effect where it takes energy to convert a liquid (sweat) into a gas. The energy needed to do this is heat removed from the surface of your skin. Our skin also conducts heat directly to the air without the help of evaporation.

Any temperature air that is blowing across a component that is hotter than the air is better than no air flow.

[SARGE]

So, all the exhaust fans in a case simply gets the heat out so it doesn't build up to a hotter degree. The incoming fans don't really do anything beneficial unless bringing in air that is cooler than the temps inside the case. My next project may be building an identical system side-by-side, use same cpu cooling fan only whether stock or liquid, and absolutely no case fans whatsoever. And compare readings. That will be fun...and maybe even bring surprises.

[David M]

The incoming fans create a pressure differential across the blades. The greater the number of pressure differentials (fans) the greater the air flow through the case. Therefore the sooner waste heat gets removed from the case, reducing the increase in internal heat.

What would be interesting Sarge is to measure the effectiveness of case fans. Start by running no case fans and measure the temperature. Run one case fan and then measure. Run up to four fans and plot each temperature. You could also test and see if front or rear fans are more effective, if there any difference at all.

[rwest]

Top fans too. Since heat rises. All it seems it would do , is push the heat down away from the exhaust fan at the rear of the case. Especially now that the PSUs are at the bottom of the case and the exhaust fan is near the top. or is a top fan exhaust?

[David M]

Upper fans are supposed to be exhaust because heat rises....why try to fight the laws of physics?

[rwest]

Okey dokey.

[SARGE]

Boy howdy, do you guys know how to give a guy a project. Then David starts writing about pressure differentials across fan blades. C'mon, I am in Texas.

[SARGE]

Originally Posted by David M The incoming fans create a pressure differential across the blades. The greater the number of pressure differentials (fans) the greater the air flow through the case. Therefore the sooner waste heat gets removed from the case, reducing the increase in internal heat. What would be interesting Sarge is to measure the effectiveness of case fans. Start by running no case fans and measure the temperature. Run one case fan and then measure. Run up to four fans and plot each temperature. You could also test and see if front or rear fans are more effective, if there any difference at all.

I can do all that with the case I have, Corsair liquid cooler monitors and Asus monitors. . Should be fun

[birddog_61]

Sarge the temp you are reading for components is in Celsius, so you want your components to stay under 80C generally which is 178F, the air you are using to cool is 100F lower in temp than the components its cooling.

[SARGE]

Then you have the psu on the bottom with its fan blowing out the bottom of the case onto the floor. Go figure.

[SARGE]

Originally Posted by birddog_61 Sarge the temp you are reading for components is in Celsius, so you want your components to stay under 80C generally which is 178F, the air you are using to cool is 100F lower in temp than the components its cooling.

Guess am doing ok. CPU temp is 24C and mobo is 28C. The fans are even keeping my legs cool.

[David M]

Originally Posted by SARGE Then you have the psu on the bottom with its fan blowing out the bottom of the case onto the floor. Go figure.

PSU's take in air at the top or bottom, (depending on how its mounted), or front and blow air out the back of the case. Place a sheet of paper against it to confirm this.

[SARGE]

Originally Posted by David M PSU's take in air at the top or bottom, (depending on how its mounted), or front and blow air out the back of the case. Place a sheet of paper against it to confirm this.

PSU (Corsair) has fan on bottom, Corsair case has opening on bottom, so figure they want it blowing out the bottom. Always seems weird to me.

[David M]

As I said, put a piece of (tissue) paper against the opening and see for yourself which way the air is flowing.