Dual Loop versus Single, the facts

[Nickel020]

Thanks for doing this, as always it's great stuff!

Is there any chance you could put this and the other white paper into a PDF for easy printing? This is the kind of stuff I like to have a hard copy of and make notes on.

[gabe]

Dare I post among these giants of the group....
Sure.

Interesting read. Nice work...

However, Trekkies, don't talk about the force, that's Star Wars...

But THANK YOU for not calling us Trekkers. I wish they had never started that.

I have edited my post to "Jedi Masters" instead of "Trekkies". Sorry for the historical confusion .

That's a fantastic post. I wonder what the power draw is at load?
@Gabe: How much do you feel that temperatures would suffer under the following conditions:
Dual MCP350's instead of dual 355s?
Or using a single MCP 350.
I would imagine that it would be quite easy for one of your many clients to add a dual radiator to their existing loop with your products.

If you refer to Part I of this article, you will observe that flow rate has a nominal impact on the water-blocks that we are using in this setup. See below regarding using (1) pump.

Great guide! I still wonder, though... is it better to have two pumps under one top at one point in a loop, or two pumps at different points in a loop?

Also, there's probably a really good guide out there, but I can't seem to find one: Anyone know how much of a performance gain you get with two pumps under one top instead of just one pump?

As long as you have two pumps in the same loop, irrespective of their position in the loop, you benefit from the redundancy factor and this is a huge plus for a high end system.

(1) pump instead of (2), see below..

awesome review! looks like single loops wins. now if you were to add one more twist, which one would win in this scenario: a single combined loop with only one pump, or a two separate loops with a pump in each loop? basically, the only thing that's changed is that the combined loop with one less pump. taking one pump away would mean less pressure/flow, but that also means that the heat from that pump is not dumped into the loop. so now, any ideas which one would win?

1. The heat from the pump that goes into the system is less than 3W, compared to ~550W generated by the CPU&GPU devices (in SLI config). It's less than 1% of the overall load, thus negligible.
2. Part I of this article demonstrated the limited effect of flow rate variations on this generation of waterblocks, so the performance loss would also be nominal.
3. In general use and by simple virtue of the asymetric load (load ratios of devices vs. heat exchangers), the serial configuration would still pull comfortably ahead.
4. In extreme use, there is no question that dual loops would be ahead but the limited scope of this usage model does not infirm the conclusions of this article.
5. Using (1) pump instead of two certainly reflects the majority in terms of usage model; from a performance and economic standpoints, this seems like the sweet spot; on the other hand, one could argue that when people invest so much money in hardware, reliability alone could easily justify the investment for a second pump. Up until now, dual loop setups have been more complex and/or often difficult to implement because of space constraints; however the introduction of the MCR-Drive series of radiators with integrated pump considerably simplifies the integration task, particularly in light of the upcoming new generation of Radiators that can now operate horizontally (hint hint hint ).

Good! Another very informative post, big thumbs up.

I never really understood the multiloop train of thought other than decreasing restriction. With restriction in mind, a single loop with just one pump like suggested is what i would really like to see as that is what i'm using atm.

How important is flow for a sinlgle loop, especially with 2 videocards?

Keep up the great stuff Gabe!

See Part I, but keep in mind that the effect of flow is highly dependant on the type of water-block that one uses. Unquestionably, F/C blocks with simple channels for example will be much more sensitive to flow rate than the micro-pin technology that we employ; opposite to this argument however is the fact that current graphic dies have a much lower internal thermal resistance than CPU's due to their huge footprint, which results in lower temps than CPU's. Thus the loss of a few degress may not be as critical as it would be with CPU devices.

Nice testing indeed. . .but, all these results are with 355's. I'm curious what would happen to the results if 655's were used instead. There are those out there that flat out refuse to use DDC's for whatever silly reasons they believe in and this testing really doesn't help them.

The absolute temperature values would differ, but the trends wouldn't.

Thanks for doing this, as always it's great stuff!

Is there any chance you could put this and the other white paper into a PDF for easy printing? This is the kind of stuff I like to have a hard copy of and make notes on.

Done! http://www.swiftnets.com/Technical/T...l_Articles.asp

[Genesis:.]

very nice article, i'm looking forward to a part three for sure (if there will be one?). i guess its single loops from now on

[Blueking]

very nice article, i'm looking forward to a part three for sure (if there will be one?). i guess its single loops from now on

Not for people who want difference colour in water :P

[StAndrew]

Outstanding! Thanks gabe!

Just a thought:

I was pretty much able to predict how it was going to turn out before reading past your list of parts. When you have that much radiator power, there wont be much difference between a dual and a single loop.

Can you run this test agian, but with a single 120 and a 240 to see the other extreme? While we will all know whats going to happen if we run two 470's on a 120, Im interested to see how the CPU does in a dedicated 120 loop vs a shared loop.

All in all, this just goes to show that its more beneficial to spend the extra money on a bigger/extra rad instead of a second pump, res, more tubing, etc...

[gabe]

Outstanding! Thanks gabe!

Just a thought:

I was pretty much able to predict how it was going to turn out before reading past your list of parts. When you have that much radiator power, there wont be much difference between a dual and a single loop.

Can you run this test agian, but with a single 120 and a 240 to see the other extreme? While we will all know whats going to happen if we run two 470's on a 120, Im interested to see how the CPU does in a dedicated 120 loop vs a shared loop.

All in all, this just goes to show that its more beneficial to spend the extra money on a bigger/extra rad instead of a second pump, res, more tubing, etc...

One needs to understand that the fundamental law being illustrated in this article is load ratios. With less cooling capacity, temperatures will substantially scale up, but as outlined earlier given the asymetric nature of the load, the outcome will remain the same (serial wins).

In normal usage, your CPU-dedicated 120mm radiator will see ~120 Watts at full CPU load, whereas in a serial loop composed of a 120 + a 220, this load will be shared by the ~equivalent of a triple rad, or ~40 Watts per 120mm fan if you will. As far as your triple SLI is concerned, at full load your dual rad currently "sees" ~360W, that's 180W per 120mm fan. If you serialize, this value will drop to 120W!

[Biffa]

Not for people who want difference colour in water :P

Just use different colour tubing?

[wesley]

until now, dual loop setups have been more complex and/or often difficult to implement because of space constraints; however the introduction of the MCR-Drive series of radiators with integrated pump considerably simplifies the integration task, particularly in light of the upcoming new generation of Radiators that can now operate horizontally (hint hint hint )

That sounds great, horizontal mounting will be very cool! I heard of rumors of a new type of Drive radiators. Any approximate ETA? :-)

Wes

[gabe]

That sounds great, horizontal mounting will be very cool! I heard of rumors of a new type of Drive radiators. Any approximate ETA? :-)

Wes

These are sheduled for release mid-July.

[Martinm210]

Just use different colour tubing?

Just what I was going to say. Off topic, but I used to have to clean my system every 3 months using glycol/dye products. Since I've switched to straight distilled and some PTnuke...I've since been running the same loop for over a year and the water and UV tubing still looks perfectly clear.

You can still run multiple colored tubes if that's what floats your boat...

[Martinm210]

These are sheduled for release mid-July.

Nice!

[Biffa]

Just what I was going to say. Off topic, but I used to have to clean my system every 3 months using glycol/dye products. Since I've switched to straight distilled and some PTnuke...I've since been running the same loop for over a year and the water and UV tubing still looks perfectly clear.

You can still run multiple colored tubes if that's what floats your boat...

I've been using Feser 1 for years and not had any major problems apart from staining of some tubing. But recently took a loop apart when switching from LGA 775 to 1366 and the inside of the CPU block had some gunk in the pins.

So I've got a silver coil, some PT Nuke and plenty of distilled

[wesley]

These are sheduled for release mid-July.

Sweet. I have been on the Drive for about a month. It's ridiculously simple to set up a single loop. Took me about an hour or 2 to set up and the temps are great.

Wes

[Vapor]

A horizontal MCR-Drive? Sign me up! I have just the use

[Alexandr0s]

Sounds great! Will it be possible to both mount it in the bottom and the top? Because the way I invision it, the runs upside down in one of those positions.

[Johnny87au]

ha, nice guide man.. Always new 1 loop was the way to go.. less tubing and better temps.. What more can you ask for

[StAndrew]

One needs to understand that the fundamental law being illustrated in this article is load ratios. With less cooling capacity, temperatures will substantially scale up, but as outlined earlier given the asymetric nature of the load, the outcome will remain the same (serial wins).

In normal usage, your CPU-dedicated 120mm radiator will see ~120 Watts at full CPU load, whereas in a serial loop composed of a 120 + a 220, this load will be shared by the ~equivalent of a triple rad, or ~40 Watts per 120mm fan if you will. As far as your triple SLI is concerned, at full load your dual rad currently "sees" ~360W, that's 180W per 120mm fan. If you serialize, this value will drop to 120W!

From my understanding, if you are using too many rads for this setup, you are removing the radiator cooling abilities as a factor in the change of temp. The temp differences between each loop will be based solely off the flow rate and how the blocks are affected by such.

Further, in my experience, many users have temp issues because their radiators are inadequate for their setup. They feel that a dual loop will correct this, but fail to understand that any amount of radiators can only dissipate a set amount of heat, regardless of the setup.

Anyways Im way behind the learning curve on the thermodynamics involved; I just wanted to see the opposite end of the spectrum .

[skinnee]

A horizontal MCR-Drive? Sign me up! I have just the use

You don't get to move to VaporBench v4 for a while yet.

[gabe]

Anyways Im way behind the learning curve on the thermodynamics involved; I just wanted to see the opposite end of the spectrum .

I understand your curiosity, sorry, these tests are very time consumming, and I had to pick what my gut feeling told me was the most commonly used high-end setup.. I had the choice between two duals, one dual + one triple, and two triples (not even looking into quads..). I picked the triple + dual, because I know it fits in many popular full tower cases like the cosmos S and so forth. The fact is, if I'm just looking at my sales statistics, I can tell you that single 120's are on the brink of extinction in my market space.

[Philwong]

Gabe, can we've another round of testing on the impact of flow rate for a single loop? Is it really necessary to run 2 pumps for multiple blocks and rads?

Phil

[gabe]

Gabe, can we've another round of testing on the impact of flow rate for a single loop? Is it really necessary to run 2 pumps for multiple blocks and rads?

Phil

No it isn't necessary, but several factors led me to test with two pumps:
1. apple to apple directly comparable data
2. I do like the redundancy factor for a high-end loop
3. my bench is setup with MCR Drive units. it's so easy to setup, it's a dream come true (for me).

I removed the XT from the loop now, as I am testing the new Apogee LP (low profile for 1U and space constrained applications), so this will have to wait for now. but I do see the economic value of it, so Im not against it.

But to answer your concern more directly: if you now have SLI graphics cards connected in series, you would benefit from parallelizing them.

[Church]

gabe: btw, such sales statistics imho can be very interesting for us aswell. Of course, actual numbers might be trading secret, but how about elaborating us at least in relative ammounts/percentages of popularity of different models? And other data too .. like i recall few times flamewars about reliability of D5 vs DDC .. i wonder which wins from vendor standpoint with actual RMA numbers on hand . I'm shure that any big vendor with real data/statistics of several orders bigger then that of even any single LC shop can have, has lot of such interesting information available only to him that can tell final word in several flame wars arround here

[Vapor]

You don't get to move to VaporBench v4 for a while yet.

I'm talking about my daily system

[StAndrew]

I understand your curiosity, sorry, these tests are very time consumming, and I had to pick what my gut feeling told me was the most commonly used high-end setup.. I had the choice between two duals, one dual + one triple, and two triples (not even looking into quads..). I picked the triple + dual, because I know it fits in many popular full tower cases like the cosmos S and so forth. The fact is, if I'm just looking at my sales statistics, I can tell you that single 120's are on the brink of extinction in my market space.

One of these days I might do some testing of my own... Im quickly learning just how expensive and time consuming these can be, and Ive yet to start . Thanks for the honest reply (ps, I buy 120's ).

[Bheem]

Gabe, thank you very much for looking into this topic. I am actually adding onto my loop pretty soon, which is a cpu-only loop at the moment, and I was really wondering whether it would be worth all of the trouble to add an entirely new loop for 2 new cards, or if I could manage them within one loop with some minor adjustments (will probably add an external 360 rad or internal 240 to my 800D). Perfect timing.