Water vs Air Cooling revisited

[dookulooku]

Ok, I see aigomorla closed the last post. I'm not here to debate water vs air ... I'm just here to refute his response.

I said:
"But it (water) can't dissipate 500W from a single source (with small contact area) because of water's low conductivity."

Aigomorla said (thermal conductivity):
Air 0.025
Water (liquid) 0.6

However,
1) In air cooling, it's the heatpipes that carry heat away from the IHS
2) In both forms of cooling, air ultimately carries away the heat.

You don't directly cool the IHS with air in air cooling! Granted there's also a metallic water block for water cooling, but that's clearly not where the emphasis is.

If you put a 500-lb block of copper onto an IHS, it would cool much faster than pouring water onto the IHS, as long as there was something to cool the copper. Why do you think the good water blocks have lots of grooves? Or why is the pump pressure important? It's because it's necessary to improve water's thermal conductivity.

Feel free to close this. We all know that water is better if you're cooling 150+ Watts. But if you're just running a 45 nm dual-core processor (even overclocked), there's not much difference between air and water. And with the new super-sized air coolers, like the V10 and V12, you'll probably have to get to 180+ W before we see a difference of more than a few degrees C.

 

[Billb2]

Originally posted by: dookulooku Why do you think the good water blocks have lots of grooves? Or why is the pump pressure important? It's because it's necessary to improve water's thermal conductivity.

With air cooling, why do air coolers have fins? And why is fan pressure important?
Just like fins and flow rate in water cooling, fins and fans improve the rater of heat transfer (to the air) in air cooling.

Water blocks can keep a CPU cooler than an air cooler because the water block can remove heat faster than a heat pipe. All things being equal, a water block that can remove 150W of heat (or 45 W for that matter) will run a CPU cooler than a heat sink that can remove 150W of heat (or 45 watts).

 

[WoodButcher]

OK, let's say your right. Why can't the TRUE keep my Q6600 G0 below 40 at load? maybe I shouldn't OC? my waterloop rarely tops 32 c unless I run prime not to mention my vid card at 36 or the NB.

 

[Rubycon]

Water can approach ambient at a given capacity easier than air. As the load increases one must increase the surface area and/or number of heat pipes as well as increase airflow to keep the target at the desired temperature.

Water cooling has limits too. As the water temperature heats up the block will not keep the core below nearly as cool. The deltas are nearly the same. It's a lot easier (and quieter!) to increase radiator size to keep up with an increasing load.