Radiator Sandwich / Stacked Radiators / "SLI-Radiators" Test results

[HESmelaugh]

I generally agree on your "lots of little things make a difference" theory. As soon as someone sends me better barbs, I'll use 'em! :-)

I attribute the non-effect of the fan speeds simply to error in measurement. The device I use for logging the temperatures has a resolution of only 0.5 degrees, so the difference might simply be smaller than that. Apart from that, even with long test runs, there's always a margin of error. So I would say in reality, the results are very close but not, as it seems from the data, identical.

[Eddie3dfx]

Interesting results.. Thanks for the test.
I wonder how it would compare to a PA or even 1 more set of fans on the top or 2 more sets of fans for the top and bottom.

[Naja002]

My approach to testing this came from reading about two other, similar tests that showed next to no effect for the sandwich vs. just one radiator. It seemed like the air got so warm after the first radiator that it just didn't do anything for the second one anymore.
That's why my focus was on verifying or disproving the hypothesis: Radiator sandwich is no better than single radiator. I must admit that I just didn't test enough scenarios, but as I said: I'll do more runs when I find the time.

In the pic below--if the air flow is reversed...I would expect the results (no effect) to be as you stated above. Air/water flow is important in this type of setup and, again, I could be wrong....but it seems like common sense to me.

[andressergio]

I love this !!

Thinking of getting another Black Ice 360GT to do it...

Thank you
Sergio

[HESmelaugh]

I think I see what you mean, Naja002. With the airflow in the wrong direction, you'd get relatively warm air blowing on relatively cool water, right?

The two options should definetely be compared to each other.

I'll start a list of scenarios that should be tested in the first post (tomorrow, though. On this part of the globe, it's getting really late).

[Naja002]

Right. If the ambient air goes over the coolest water first its going to get slightly warmer (1.5C or less) which will be removing heat from that water....it will then go over the much warmer water--removing the bulk of the heat. Its about temp difference. The air going over the coolest water will remove some more heat (energy), but not enough to increase the air temp v. the water temp in the hottest rad. So, the air should still have a significant temp difference compared to the water in the hottest rad....and remove the bulk of the heat as it passes through.....

The reverse would just be reheating cooled water.....

[SNiiPE_DoGG]

The reverse would just be reheating cooled water.....

no. water temp is always higher than ambient, you would never get "reheating" of the water. the delta air-water would just be smaller

[HESmelaugh]

- Update -

Added the following list of test-scenarios to first post:



Scenarios for further testing:

In the meantime, a lot of interesting suggestions have come up. Here's a list of all of the ideas that should be tested. Please contribute! :-)

- Two radiators separately vs. stacked radiators
- Stacked radiators with a total of six fans
- Stacked radiators with a total of nine fans? (Overkill?)
- Stacked radiators vs. PA120.3 (testing in progress on this one)
- Airflow going from first to second radiator vs. airflow going from second to first radiator (as discussed in posts 29-33)

[Shocker003]

no. water temp is always higher than ambient, you would never get "reheating" of the water. the delta air-water would just be smaller

Reheating of water woun´t happen but the aim of the second rad is defeated.
Front mounted rads perform better than rear or top mounted rads that has to draw warm air from inside the case.
The direction of air flow/which rad gets the water first in stacked rads will play an important role when the configuration is being used. I have tried single rad with front and later back mounts and i noticed that i lost about 4~5°c difference in temp with front mounted rad but other hardwares get heated up from the heat being dumped in the case. Thats why i went with a external mounted rad. The bottom line is that when the water flow from rad1 to rad2 and the air flows thur rad1 to rad2; the water exiting the rad2 will not loss enough heat due to warm air coming from the first rad1

[silverphoenix]

Reheating of water woun´t happen but the aim of the second rad is defeated.
Front mounted rads perform better than rear or top mounted rads that has to draw warm air from inside the case.
The direction of air flow/which rad gets the water first in stacked rads will play an important role when the configuration is being used. I have tried single rad with front and later back mounts and i noticed that i lost about 4~5°c difference in temp with front mounted rad but other hardwares get heated up from the heat being dumped in the case. Thats why i went with a external mounted rad. The bottom line is that when the water flow from rad1 to rad2 and the air flows thur rad1 to rad2; the water exiting the rad2 will not loss enough heat due to warm air coming from the first rad1

The significance of this greatly depends on the rate of airflow.

[HESmelaugh]

would the flowrate of the coolant have any impact on this?

[septim]

can you add in scenario:

rad 1 - rad 2 - 38mm fan

[ultimeus]

thanks for this tests, i'm looking for your next review since i'm building a similar watercooling setup.

[HESmelaugh]

can you add in scenario:

rad 1 - rad 2 - 38mm fan

Done. I don't know if I can do it with 38mm fans though. Firstly, because I don't have three of a kind right now (that would be a minor problem though) and secondly, because it's then less comparable with all the other scenarios.


Just let me throw this idea out there: Let's assume that Skinnee (or someone else) also gets a chance to test stacked radiators. How about I test with 25mm fans and someone else with 38mm fans (for all the scenarios)?

[masxerofkartis]

How did you screw the rads together?

[gmod]

Hey ive got a extra TC 120.2 maybe I can sandwich that with 1 of my TC 120.3's Wonder if that would make much difference on my Gtx280's

[HESmelaugh]

How did you screw the rads together?

Like this:



Each fan is attached to the lower radiator at two diagonal points and to the upper radiator at the other two diagonal points.

[Naja002]

no. water temp is always higher than ambient, you would never get "reheating" of the water. the delta air-water would just be smaller

Agreed. Just trying to keep it simple for those going through the mental exercise...

[JvT]

If the flowrate is to your concern and you want to avoid elbow fittings, how about turning one of the radiators 180 degrees, so that the fittings sits opposite of one another.
Thats how I have my 2 rads in my TJ07.
Something like this:

[Shocker003]

Agreed. Just trying to keep it simple for those going through the mental exercise...

The significance of this greatly depends on the rate of airflow.

Well i rest my case for now cos am a wc noob.
Waiting for test results

[HESmelaugh]

- UPDATE -

Here are the CPU minus Ambient temperatures including a comparison to the PA120.3:



This has also been added to the first post.

Cheers,
Shane

[Martinm210]

Superb work! Thanks so much for taking the time and putting in all the effort to try this, it's something that has been asked about before.

I really didn't expect it to do as well as it did. Generally I've found the double thickness is really only good for about a 10-15% gain if that over a standard thickness. Looks like this sandwiching may be work 30% or more...that's very good!

I think this sandwiching is getting additional gains because of fan turbulence internally. Just like the shroud testing I found there was an optimal distance from the radiator, and I can only attribute that is due to some sort of fan scrubbing turbulence thing when the fan is close to the fins.

Anyhow, this is very interesting, it appears to do better than the double thickness rads and costs less....wow!

Any thoughts on sound quality differences?

Thanks!! Amazing work!!

Off to strapping a few rads together for my regular system...

[HESmelaugh]

I was surprised myself that the sandwich beat the PA. Just to make sure, I did two test-runs each.
And I have to admit that I really don't have enough data to be able to understand how or why the sandwich is so effective.

On a completely different note: How great would two BlackIce rads with LED-Fans in between look? :-)

[Eddie3dfx]

I was surprised myself that the sandwich beat the PA. Just to make sure, I did two test-runs each.
And I have to admit that I really don't have enough data to be able to understand how or why the sandwich is so effective.

On a completely different note: How great would two BlackIce rads with LED-Fans in between look? :-)

So all you used was one set of fans betwen the radiators?
25mm too.. hmm
Did you try it with more fans, middle & top?

[NaeKuh]

On a completely different note: How great would two BlackIce rads with LED-Fans in between look? :-)

ahem..

2 fessers 480's with 8 sanaces in the middle and 3 or 4 DDC's


i'll tell you when oracle is finished..
This will be semi bling build...