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PostPosted: Sun Nov 08, 2009 12:41 pm 
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Joined: Wed Sep 03, 2008 10:31 am
Posts: 7
Location: Romania
MikeC wrote:
I'll have to set up an i7 system to see what those CPUs really pull at the 2x12V socket.

More experiments are in order. The gist of what I am trying to determine:
1) Does C/W of a heatsink/fan stay the same as CPU power is increased?
2) If not, how much more power is needed for C/W to change? Is there a consistency to that change? ie, for every +10W, C/W decreases (or increases) by 10%, or whatever pattern can be discerned.
3) Does the ranking of SPCR's top low-airflow coolers stay the same when a CPU of higher TDP is used?
4) Finally, if the decision is made to add a high power CPU test, what should that power level be?


The fact that you are considering to put the theory into practice, and maybe find out other theories based on the real-life results makes me very happy, and I salute our decision. :D

But I must make some further observations regarding your questions...

1 + 2 - I see you are trying to find an accurate way to extrapolate what you've tested so far, but in my opinion you won't. I hope I'm wrong because if you do, then it would be a very interesting theory.


3. No, they won't in my opinion. Also, to answer your remark...
MikeC wrote:
Not a good example -- the CM Z600 will lose at low airflow against the TR HR-01+ with any CPU and neither will cool effectively enough w/o a fan on an i7.

... I give you this link, where you'll find the test conditions for this table. Or you can look here and here, the test conditions are the same.

So in my compatriot's tests, between CM Z600 and TR HR-01+ there is a 15c difference in fanless mode, and about 3.5c using a 800 rpm scythe slipstream fan. So YES, I think that CM Z600 is a VERY GOOD EXAMPLE. I don't consider Scythe Orochi an option because it's just HUGE.

Does the ranking of SPCR's top low-airflow coolers stay the same when a CPU of higher TDP is used? Well, since you don't consider CM Z600 a top-dog from your tests, probably they will remain unchanged. :(


4. if the decision is made to add a high power CPU test, what should that power level be?

I am deliberately not taking into account the power level notion to simplify the argument. So, in my opinion the answer to your question is the HOTTEST Intel CPU (or an overclocked Intel CPU) that the current best low-rpm cooler (CM Z600 with a 800 rpm fan - as later in time another one better will surely appear) can cool under load at ~ 75c at your given ambient temperature (or maybe ~ 10c below Tjunction Max of that INTEL processor).

But hell, I'm just a member of your forum, why should you listen to me? Please find out for yourself... :)


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PostPosted: Sun Nov 08, 2009 10:26 pm 
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Joined: Sun May 10, 2009 12:47 am
Posts: 43
Location: Here
To give you an idea of how hot a Core I7 cpu is take a look here:

http://translate.google.com/translate?h ... ount%3D393


As of former owner of both the HR-01+ and the Nirvana I can tell you because I tested them both the HR-01+ is not very good:

http://translate.google.com/translate?h ... count%3D99

Google translation on both links.

Personally I don't understand why the Z600 has been getting such bad press around the net. Apart from the size it probably was the most versatile heatsink before the Megahalems appeared.


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PostPosted: Mon Nov 09, 2009 4:38 am 
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Joined: Sat Oct 31, 2009 4:44 am
Posts: 7
Location: The Netherlands
Arguments like these are good, we should always keep an eye on the methods we apply to make tests scientifically sound. Unfortunately online arguments derail more easily than a tete a tete discussion. I think we should never assume a testing methodology is flawless, and it's perfectly fine to point out possible confounds, as long as it's done in a constructive manner so we all can learn from it.

As for myself, I would forgo extrapolation when real results are achievable with reasonable effort. To illustrate the risks of extrapolation, the blue line from the graph on page 1 shows a change at the penultimate point, because the last data point buckles the trend. That data point may be a fluke, and every extrapolation derived from it may be off the mark.
What speaks for the extrapolation is that these curves are not uncharted territory, we see this bottoming out consistently.


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 Post subject: Re: ZEROtherm Nirvana CPU Cooler
PostPosted: Mon Nov 09, 2009 4:59 am 
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Joined: Tue Nov 04, 2008 6:03 am
Posts: 621
Location: Sweden
reddyuday wrote:
It is the heat generated by the CPU that matters in evaluating the cooler.
Very true!

Unfortunately the heat isn't enough for a perfect comparison if the size and shape of the IHS of the CPU used for testing differs from the IHS on my intended setup.

The typical socket 775 CPU has an IHS that's considerably smaller than that of socket 1366 CPUs.

Cheers
Olle


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 Post subject: Re: ZEROtherm Nirvana CPU Cooler
PostPosted: Mon Nov 16, 2009 5:27 pm 
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Joined: Sun May 31, 2009 9:46 am
Posts: 94
Location: British Columbia
Olle P wrote:
reddyuday wrote:
It is the heat generated by the CPU that matters in evaluating the cooler.
Very true!

Unfortunately the heat isn't enough for a perfect comparison if the size and shape of the IHS of the CPU used for testing differs from the IHS on my intended setup.

The typical socket 775 CPU has an IHS that's considerably smaller than that of socket 1366 CPUs.

Cheers
Olle


True. Here's a picture to illustrate the size difference.

Image


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