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Does the orientation of a heat sink change its cooling power

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June 29, 2007 1:23:35 PM

Hi,

I currently have a number of cooling related issues with my PC, but in my opinion have OK equipment for what I am doing - I do not over clock the PC etc.

The main question I have is, does the orientation of a heat sink change it's effectiveness for calling the CPU?

E.g. If you have a cooler like the "Enzotech Ultra-X", does the bend of the heat pipes make a difference to how cool the CPU will become if they are either going up or down.

I have a midi tower case and therefore when mounting a number of heat sinks, am limited to either the heat pipes going up, across then down, or down, across then up to the fins - Is there a preferred direction for these?

If I take this a step further to add clarification, if my mobo was laying flat on the floor, when the heat sink is connected, the contents of the heat pipes will drop (by gravity) to above the CPU, then if heated up, will evaporate and make they way up to the fins/fan - by using a midi tower, does this process still work, or should I look at getting a specific type of CPU cooler?

Hopefully you may be able to provide some insight to this, any feedback would be welcomed.
June 29, 2007 2:19:34 PM

The majority of home users have their mobos oriented in a vertical (standing) position. Manufacturers take this into account when making heatsinks. My best advice is to follow the instructions given by that particular company on the orientation of the heatsink as they probably designed it to work best in that specific position.

Typically the position shouldn't affect the cooling much if at all. The time when it might affect cooling the most is when there is a fan attached to the side of a heatsink rather than a downblowing fan. If its side-mounted fan then it is usually best for case temps to have the fan blowing towards the rear exhaust fan on the back of the case. This usually helps keep internal case temps down and in turn that usually helps CPU temps as well as temps for other components. That is the only time the position should make hardly any noticable difference whatsoever. So in closing, just go by what the manufacturer says first and see how that works for you.
June 29, 2007 2:25:38 PM

Talon,

Thankyou for your response, I will look at the manufactors info - if anyone else have any other view, please post.
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June 30, 2007 1:26:32 AM

A better orientation of the CPU Heatsink is to point the fan upwards and have a blow whole at the top as an exaust. If you're using Antec 900 with a 25mm fan on the top of the case, you should point the fan towards the top and let the hot air expell from the top.
June 30, 2007 2:30:57 AM

Go read the recent anandtech review of that HSF...
June 30, 2007 3:51:43 AM

Quote:
A better orientation of the CPU Heatsink is to point the fan upwards and have a blow whole at the top as an exaust. If you're using Antec 900 with a 25mm fan on the top of the case, you should point the fan towards the top and let the hot air expell from the top.

Interestingly, I tried this, but I actually got better CPU temps in my 900 by putting the fan over the first RAM slot and blowing towards the back of the case.

I think the reason is that if the fan is on the underside of my Scythe Ninja, it is pretty close to the top side of the video card. So, it is actually pulling warm air from the video card across the CPU, causing higher CPU temps.

Now, I'm only talking a couple degrees, but when overclocking, every little bit matters.

-TyShoe
June 30, 2007 5:52:20 AM

And, by all means do the other reviews.

My preference for anandtech at present is that they have tested a number of HSF's on a common test bed, so they present more of an apples-to-apples review. If their methodology is a bit off, so be it, but it will be a bit off by an equal amount for all of the tested HSF's.

As well, they tend to go a bit further, breaking down some comparisons by commenting on the downward facing HSF vs. the side-mounted units. I am not always in agreement with their fan choices, but at least if there is a fan to choose it will be the same on their tests.

They are also not above calling a spade a spade, and will point out MFG flaws that could / should be corrected to improve the product. I'd like to know if their comments on the Ultra extreme's mounting system pre-release led to the improved release version...
June 30, 2007 6:16:34 AM

Quote:
And, by all means do the other reviews.

My preference for anandtech at present is that they have tested a number of HSF's on a common test bed, so they present more of an apples-to-apples review. If their methodology is a bit off, so be it, but it will be a bit off by an equal amount for all of the tested HSF's.

As well, they tend to go a bit further, breaking down some comparisons by commenting on the downward facing HSF vs. the side-mounted units. I am not always in agreement with their fan choices, but at least if there is a fan to choose it will be the same on their tests.

They are also not above calling a spade a spade, and will point out MFG flaws that could / should be corrected to improve the product. I'd like to know if their comments on the Ultra extreme's mounting system pre-release led to the improved release version...


As heatsink reviews go, AT does a great job, but I personally have issues with thier "side-blowers are better than top-blowers" stance/conclusion. Clearly other sites are getting results that conflict with that and AT hasn't explained that away sufficiently yet. In fact, the X-bit labs link above has almost the opposite effect (top-blower out-performing side-blowers). Obviously there are differences in fan speeds in use and such that you need to look for, but even accounting for that, it leaves questions. It could be that sites that test in a case with a side-vent will favor top-blowers and sites that test with no side vent and all system fans turned off will favor side-blowers.

I just think AT is jumping the gun on thier general conclusion, based on thier setup (and yes, I know they've tried with and without the case fans on and with and without the side panel on, but the differences are still there and so there must be some explanation).

Anyway, based on your comments above, if you like AT's reviews, I bet you'll love MADSHRIMPS reviews. He tests each heatsink with stock fan and a common (low noise) fan, both at low and high speed and also "tells it like it is" (he also often tests with a common high-speed, high-noise fan in the charts at the top of the page).

His current list of heatsinks on the most recent test platform is likely missing a few you'd like to see, but he's working on that as time permits. His earlier roundups include some heatsinks only tested on the AMD platform.
June 30, 2007 6:43:39 AM

I know of Madshrimps, and (H)ocp, et al.

My point was, I guess, that Anand's test lab has used the same reference test bed for a number of HSF tests. While one might have a differing opinion of the conclusions that they draw, the numbers (seem) to all be derived using the same base starting point. I'm not arguing that their conclusions are the least opinionated, just that their raw data is the most consistent.

Just going from their raw data, I can see why they draw the conclusions that the do on side cooling vs. down-cooling HSF's, and have indeed been of that opinion myself ever since I got my arctic freezer (4?) years ago. It is nice to finally see raw data that tends to support my opinion, but I'm open to other theories if you have one to put forward.
June 30, 2007 7:56:08 AM

Quote:
I know of Madshrimps, and (H)ocp, et al.

My point was, I guess, that Anand's test lab has used the same reference test bed for a number of HSF tests...


...oh, I agree that it's nice to see the largest pool possible, all tested on the same platform, and that's one reason I like Madshrimps' round-ups as well as AT's. The other thing I really like about MS is the use of a common low noise fan on each heatsink, so we can see results based on how many people like to run thier system - without getting a headache :)  (obviously this may not be the most important criteria for everyone).

Quote:
Just going from their raw data, I can see why they draw the conclusions that the do on side cooling vs. down-cooling HSF's, and have indeed been of that opinion myself ever since I got my arctic freezer (4?) years ago. It is nice to finally see raw data that tends to support my opinion, but I'm open to other theories if you have one to put forward.


I also see why they draw that conclusion - it's pretty obvious from the results they're getting on thier test setup. My only quibble is that it should be equally obvious that other sites are getting conflicting results. Since that's the case, I wouldn't personally be so quick to draw such "generalized" conclusions, based on one test setup. Note that thier most recent/current explanation of this issue is that they're using a modern (C2D) chip and other sites are using an older P4 chip. But...

a. that doesn't account for heatsinks (both tower and top-down) tested on the same platform (regardless of chip in use) and..

b. the X-bit review linked above (for example) also uses a C2D chip for thier testing.

...again, I don't know exactly what's causing the difference, but my best guess at this point is that it must be some difference in the testing setup:

AT:
- closed case with all case fans disabled and no side vent (as far as I can tell)

X-Bit:
- closed "ASUS ASCOT 6AR2-B Black&Silver with three system fans from Cooler Master (120mm, 1200rpm, 21dBA)" (I wasn't able to find stats on this case when I looked earlier, but it looks like all the other cases ASUS sells have side vents)

...I'd note that they are using different cpus, likely at different voltages, generating different amounts of heat, but I'm not interested in comparing temp numbers between sites (bad idea from the get-go), only between coolers on each site.

I'd also note that they are using different fan speeds in some cases, but let's just look at the Enzo vs Zalman 9700 comparison...

On AnandTech, the Zalman out-cools the Enzo by "a relatively large margin" (~7C on the stock speed, "load" chart). And yet on the X-bit test, the Enzo out-cools the Zalman under every condition. In fact, the best the Zalman does (~73.8C on an open stand, with fan at full speed) is still short of the worst figure for the Enzo (~71.2C inside a closed case, with it's fan on low).

Of course the Enzo is also out-performing the Infinity and Noctua sinks with both one and two fan configurations, but you'd have figure out how to factor in the slower fan(s) being used on those. I picked the Zalman because it's fan is not replaceable and the Enzo is using it's own fan (or at worst, a much slower spinning one).

Note that the X-bit results are not specific to the Enzo either... both the Typhoon and Samurai (both top-blowers, with lower fan speeds) are out-performing the Zalman (most apparent in the closed-case test), yet the AT results again show a reversal of that ordering.

If this was an isolated incident, you might chalk it up to human error, but I don't have any reason to believe X-bit is any more prone to error than AT might be. As I've stated in the AT forums, I have no problem believing that AT is getting the results it's getting, but I also have no problem believing other sites are getting conflicting results.

If I had the resources to do so, I'd go buy a case with side vents (that could be taped over), a handfull of case fans, a couple cpus and a handfull of representative heatsinks and do some testing to figure out what's going on - but I don't have the scratch for that.

Sorry for rambling... to wrap up, I personally don't treat any site's heatsink reviews as the "absolute facts" about how well a cooler cools. I read reviews, pay attention to the fine-print (test configuration), look for trends, find one (or several) I might be interested in and try to correlate results on those from various sites, as best I can.
June 30, 2007 8:04:30 AM

To the OP... sorry for the thread-jack... my answer to your question mirrors Talon's - I'd look to the manufacturer's recommendations.

As mentioned, it shouldn't matter, since heatpipes use a 'wick' affect to move the fluid to and fro, but gravity can also give a boost (or slightly hinder) to this, so EnzoTech (for example) recommends that the pipes point front-back and not up-down.

IIRC someone tested this particular cooler both flat (mb on test-bed, not in a case) and standing upright (with pipes pointing front-back) and found a 1-2C difference.
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