Scaling of Cooling Performance

The Ultra-X performance was average at stock idle and below average among top coolers at stock load. As overclocks are raised, the Enzotech exhibits improved performance in the ability to cool the CPU under stress conditions. To be as fair as possible all overclocking tests were run with the Enzotech fan at the highest speed.

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At 2.93GHz the retail HSF is running at 41C, compared to 32C with the Ultra-X. This is a delta of 9C. The delta becomes greater as the overclock increases. At 3.73GHz the idle with the retail fan is 56C compared to the Ultra-X at 39C - a delta of 17C. The cooling performance of the Enzotech is much better than the Intel retail cooler at idle, but the Ultra-X does not reach the same cooling levels measured with the Thermalrights (with a Scythe S-Flex SFF21F fan) or the stock Tuniq 120. The top Thermalright Ultra-120 eXtreme, for example is at 33C at the same 3.73GHz.

We also need to compare cooling efficiency of the Enzotech Ultra-X under load conditions to the retail HSF and other recently tested CPU coolers. Load testing can be very revealing of a cooler's efficiency. A basically flat line, particularly form 3.73GHz upward, indicates the cooler is still in its best cooling range. A line that is increasing rapidly indicates a cooler nearing the end of its ability to cool efficiently. Lines which parallel the best coolers over a range of values are indicate that the coolers have similar cooling efficiency.

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The Ultra-X is very efficient in cooling in the 2.93 GHz to 3.73 GHz overclock range. As you can see in the chart the cooling is almost a horizontal line in this range. The Enzotech continues on to a highest overclock of 3.86GHz, which is short of the 3.90GHz to 3.94GHz most of the top coolers in our testing have achieved. These results are similar to other down-facing coolers. While the overclock is the best we have seen with a down-facing cooler, they are still below the top heatpipe towers. The slope of the Ultra-X in this range from 3.73GHz to 3.86GH is steeper than the heatpipe towers, indicating it is nearing the end of its range of efficient cooling.

Unfortunately, the Ultra-X is not in the same cooling category as the best heatpipe towers we have tested. We hoped this cooler might be the down-facing cooler to buck the trend, but that is not the case. Ultra-X is a decent cooler to the range just below the best, but cooling efficiency is similar to other down-facing heatpipe towers tested.

As stated many times, the overclocking abilities of the CPU will vary at the top, depending on the CPU. This particular CPU does higher FSB speeds than any X6800 we have tested, but the 3.90GHz top speed with the Tuniq is pretty average among the X6800 processors we have tested with Tuniq cooling. A few of the other processors tested with the best air coolers reach just over 4 GHz, but the range has been 3.8 to 4.0GHz. Stock cooling generally tops out 200 to 400 MHz lower, depending on the CPU, on the processors tested in our lab.

Cooling at Stock Speed Overclocking
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  • GlassHouse69 - Friday, June 29, 2007 - link

    This screams for a simple fan swap. Either a Nexus fan, a Yate loon, or a Papst 120. That with a front fan controller would make this a very decent cooler without the noise.
  • mpelle4456 - Thursday, June 28, 2007 - link

    I think it’s great that Anandtech is doing reviews on heat sinks, but I can’t get behind some of your methodology – i.e., the “highest stable overclocking” tests for heat sinks.

    There are so many, many variables at play when overclocking a computer, that unless every test was done with exactly the same components – the exact same CPU, the exact same motherboard, the exact same RAM, and so on – all the exact same hardware, with the exact same BIOS settings and software – then the test is not in any way valid.

    Tests using the same model/brand CPU’s or RAM just don’t it – there are way too many variations between different CPU’s and steppings. An Opteron 170 CCB1E 0550VPMW might perform totally different to an Operton 170 CCBWE 0609FPAW. The same is true with RAM and other similar components.

    The rest of the tests are more valuable – assuming that each of the 20 or so heat sinks were tested with the same model processors.

    The best, most useful methodology I have seen was used by Joe Citarella over at Overclockers.com -- http://www.overclockers.com/articles373/p4sum.asp">http://www.overclockers.com/articles373/p4sum.asp

    In their tests, they used a die simulator which put out a specific, precise amount of heat.
    Their results are expressed as xx C/W (x degrees centigrade cooling per CPU watt – e.g., “To calculate what to expect for other CPUs, for every watt the CPU radiates, the heatsink will cool the core by the (C/W x watts) plus ambient temp. For example, at a fan inlet temp of 25 C, a C/W of 0.25 with a CPU radiating 50 watts means that the CPU temp will be 50 x 0.25 = 12.5 C over ambient temp, or 37.5 C.”
    Unfortunately, it appears they discontinued their air cooling reviews some time ago.

  • Wesley Fink - Friday, June 29, 2007 - link

    You are correct in stating highest overclock tests need all variables to remain the same. We DO use the excat same CPU, motherboard, RAM, BIOS settings. Hard Drive, and Software/OS image for all cooler overclocking tests.

    That is why we will retest a few representative coolers and start a new database when we make to the change to a new test bed. Ot os also why we are slow to change our test beds once they are established.
  • BigMacKing - Friday, June 29, 2007 - link

    even in the same case?
    If it is, most of your cooler reviews will be worthless, unless users use the same case as you.
  • punko - Friday, June 29, 2007 - link

    I'm not the sharpest stick in the umbrella stand, but I assume the case is standing normally, so the MB is vertical and the cooler is standing "sideways".

    With the down coolers, the heat pipes may disturbe the exhaust airflow. There are two possible arrangements at 90 degrees to each other. Would this affect things?

    Note, also would apply to towers, which way do you point the fan? toward the exhaust vent?

    For this cooler, there are 4 possible configurations, as the heatpipes are only on one side.

    Is there any reason to suspect that the orientation of the cooler would have any difference?

    Making sure the heated air is exhausted from the case is key, as is making sure you have a clear passage of cool air. any chance of recirculating the warm air will reduce cooling. the Towers have the advantage as the exhaust air would be moving the air not at the MB but directly at the exaust vent.

    Just a thought
  • Tuffrabbit - Thursday, June 28, 2007 - link

    Looks like the Thermalright Ultra 120 Extreme is going to be the winner for quite some time... But please keep bringing on all contenders ! Another great bout !
  • magreen1 - Thursday, June 28, 2007 - link

    I laughed out loud
  • jebo - Thursday, June 28, 2007 - link

    I wonder if the extra "bend" in heatpipes inherent in top-down coolers is preventing them from keeping up with the side-blowing coolers?

    Either way, each review solidifies my plan to pick up an Ultra 120 extreme once I make my quad-core upgrade :)
  • strikeback03 - Friday, June 29, 2007 - link

    I'm wondering if it might be the extra length of the heatpipes before they get to the cooling fins. More heat would build up in the processor if it can't be moved away as efficiently.
  • joetron2030 - Thursday, June 28, 2007 - link

    First, I've really been enjoying these cooler tests. Very informative and I've been keeping track for my next build.

    One thing I would like to see, that I haven't seen so far, is a chart/graph that lists all of the tested coolers by weight. Considering one of the things mentioned in these tests is the weights of some of these coolers, it would be nice to be able to add that in as another point of comparison between these coolers. Unless, of course, their weights are all relatively close to one another.

    Thanks for the consideration!

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