Calculating radiator surface area

[Sprocket7]

Is there a general rule of thumb for calculating the surface area required for cooling the Intel i7 920 Cpu? For example.. So many sq-inches per degree drop required between ambient air temperature and cpu temperature.

[Bobnova]

I've seen it said a few times that a 2x120 is enough for a i7 920, while i have yet to see a 1x120 kit that kept one cool at full OC.
Hence, i'd say somewhere between 120x120 and 240x120 is the minimum.
Course fin density, fan pressure/flow, and radiator thickness all play a part.

I've never seen a comparative chart like that, though i'd like to, maybe you can convince someone to write an article about it.

[Porvalsh]

It would indeed be a very useful chart, and you may be able to interpolate off of skinnee labs charts based on wattage output of the CPU but there are a lot of different variables involved that will skew the results. Consider:

-Air Temp In
-Fan speed/CFM
-Fan Configuration (Pull or Push/Pull)
-Usage of fan ducts or not
-Radiator Type/Fins per inch
-Heat dissipation variations in peoples max OCs
-Differences in Chips

[Conumdrum]

An i7 920 can easily put out 250 watts at 4.0+. If you look at Skinees charts you can see what a rad with your speed of some popular fans will make the Delta T temps.

A 120x2 is minimum. A 120x3 is for the ones who want low speed fans and great temps.

http://www.skinneelabs.com/

[billb]

Is there a general rule of thumb for calculating the surface area required for cooling the Intel i7 920 Cpu? For example.. So many sq-inches per degree drop required between ambient air temperature and cpu temperature.
LOL..

You could calculate that for any rad, but it would have to be at a certain air/water flow and a specified heat load. So, in essence, every possible system would have it's own "rule of thumb". But then, if you did that calculation, you'd know what rad to use.

[Sprocket7]

Thanks for the link - theres a tonne of stuff to peruse once you start really looking. Thanks also for the info on i7 heat output conundrum. I'm looking at using 140mm wide radiators which are only recently making an appearance.

[Conumdrum]

Sprocket, you can still get a close measure by the sq inches of rad area 120mm vs 140mm sized rads. Just do the math. I'm sure a 140x2 is about equal to a 120x3, but I'm not mathin' right now.

[Frankenchrist]

Delta makes some monster air moving fans (210cfm) for servers that I have been using. They sound like a jet engine under full power but godamn they keep er cool. These fans are the best there is *PERIOD*