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Cooling 65W passively

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  • CPUs
  • Cooling
  • Heatsinks
  • Power
  • Product
Last response: in CPUs
January 21, 2009 12:26:13 AM

I was just wondering if any of you guys thought that it would be possible, if you had the right stuff, to cool 65W of thermal power passively? or would I need a heatsink so big that I could smash someones head in with it...

More about : cooling 65w passively

January 21, 2009 12:44:00 AM

Depends on the 65 watt cpu you're talking about, the case airflow, and finally the amount of time the cpu would spend under full load vs idle time. In short, if Dell can keep a Prescott P4 reasonably cooled with a big copper heatsink and a rear fan with shroud for good air flow through the CPU heatsink, then there's no reason to think that feat can't be accomplished with a CPU with a lower TDP.
January 21, 2009 12:47:51 AM

The TRUE could passively cool a 65w CPU in a well cooled case.
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January 21, 2009 2:23:37 AM

you talkin about the true copper or the black? anyways I was kinda wanting to build a completely silent and passive machine with reasonable means, MAYBE one rear case fan or possibly just leave it open and through out the lid lol. and I kinda wanted it to be mini at least a mini itx or micro atx but if theres a fat ass heatsink on top of it, it wouldnt bother me, just as long as its quiet. or ill just get the quietest fan possible no matter what the CFMs

yea I was putting in a dvd drive in my grandmother's dell and I saw that little bit and thought it to be interesting, the heatsink wasent even that intrequite to be honest, no more than 20 thick copper fins at best, probly less i think.
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January 21, 2009 3:59:10 AM

With no fans at all, you have somewhat of a problem. Completely stagnant air is never a good thing. Now, you could have a few case fans only, and get it pretty darn quiet. You don't want everything stagnant though, as the air in the case will just sit there and heat up.
January 21, 2009 9:40:56 AM

Thats why I suggested an open air solution, which might work. Kind of curious if it would to be honest, but if nothing else just turn on the fan or send the case back I guess.
January 21, 2009 2:54:48 PM

There are slow fans that are nearly silent, like some of those ceiling fans. A few low-cfm fans placed strategically on the hottest components would perform far better than completely passive cooling or a lone medium-cfm back fan.

And unless you have a specialty radiative case, you'll still need airflow through your case, either by opening it up or packing a few quiet fans.
January 21, 2009 6:48:56 PM

well that sound feasible. the only reason i mentioned 65W is because I wanted to be a dual-core intel and that was the lowest TDP they had for a dual-core.
January 21, 2009 8:16:50 PM

i did think about that but their caches always seem so small compared to intel's. I mean if you or someone else could present a case as to why this is insignifigant or negligbable as to choosing a processor then i'd be glad to change my mindset.
January 21, 2009 9:10:11 PM

Cach on an AMD system dose not make a difference that much. I went from a X2 4200 with 1MB total L2 cache and 2.2GHz to the X2 6000 with 2MB L2 Cache and really did not notice anything performance wise.
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January 22, 2009 1:01:22 PM

Aww c'mon... I cool my 45w Athlon X2 @2.7Ghz with a passive Scythe Ninja Mini... now the full size or the TRUE 120 is like miles ahead... so of course!
January 22, 2009 1:36:02 PM

my current system is a pent d 930 3ghz oc'd to 3.6ghz on liquid. lol I have to run it on liquid since its an ancient 90nm. yea the system im using is a pre built TEC system and the fan is loud to me.
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January 22, 2009 1:40:45 PM

Intel 45nm duals may have a TDP of 65 watts, but they really don't use anything near that. An E8200 or E7300 will probably use under 40W full load in reality.

In fact, here's a table I just found demonstrating that point rather effectively:
January 22, 2009 1:46:06 PM

good find cjl, thanks for the very informative chart quiete interesting compared to the amd's actual TDP. i guess they just over rate them fir head room
January 22, 2009 1:55:08 PM

yea i read the review on that, but like you said a bit pircey.
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January 22, 2009 2:10:00 PM

I wouldn't worry about that. Just get something like an Antec Sonata, dump the case fans, add a few of those Noctua fans instead, and get a quiet PSU. For the CPU cooler, use a TRUE or a Noctua cooler, along with another of those Noctua fans, and your total system noise should be under 20dB (assuming the GPU is sufficiently quiet).
January 22, 2009 5:20:35 PM

yea but I was kinda goin for completely quiet or a low low low low low hum.
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January 22, 2009 6:52:47 PM

That's what 20dB is. A quiet room is in the 28-30dB range, so 20dB won't even be audible unless you're practically in an anechoic chamber.
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January 22, 2009 11:44:30 PM

cjl said:
Intel 45nm duals may have a TDP of 65 watts, but they really don't use anything near that. An E8200 or E7300 will probably use under 40W full load in reality.

In fact, here's a table I just found demonstrating that point rather effectively:
http://www.xbitlabs.com/images/cpu/intel-wolfdale/pcons-2.png


TDP is a measure of thermal output not of power consumption.
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January 23, 2009 5:36:30 AM

amdfangirl said:
TDP is a measure of thermal output not of power consumption.

A chip consuming 28 watts of power isn't going to generate 65 watts of heat though. In fact, the power consumed by the chip is the upper limit for how much heat it could generate.

It's actually a measure of Intel's specified required thermal dissipation for a cooling solution, often significantly above the actual thermal output of the chip.
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January 23, 2009 9:53:25 AM

Its for system builders to design cooling systems to handle all the heat at maximum, plus a lot of extra leeway.