WC'ing with SLI - One Tube or Two?

[MattMan657]

Hey all, I've been planning some new additions to my loop, mainly watercooling a new GPU and adding in another rad. Nothing overly complex. However, IF I can swing it I'm considering going SLI. Bonus time will dictate this.

I see water cooled SLI setups on here all the time. Sometimes there are two connections for the liquid, sometimes just one. What are the benefits to these designs?

Here are two pictures I snagged from the picture thread here to illustrate my question. Not my builds, but some very nice ones so if you see yours here consider it a compliment. Thanks.



One Tube


Two Tubes

 

[bamato]

I'm actually a little confused as to how the second picture is setup. Feels like I'm missing something.

The first picture is the way I see most of the SLI setups running.

 

[RnRollie]

First one is serial, second is parallel

there are benefits & drawbacks to both types of setup... although in the end it only makes a coupld decrees °C difference.

Suggest you read the stickies, as there is some (flow) science going on with these setups

 

[MattMan657]

Couldn't find the sticky on that specific subject. Any links?

EDIT:

After Googling the subject, it seems that Parallel is beneficial for systems with perhaps a bit more restriction as it increases flow rate. While on the other hand Serial has a higher pressure. From what I've (quickly) read, it doesn't sound like there is a big delta between the two for non-overly complex systems, which is exactly my case. If I were to go SLI my setup would be...

Triple Rad w/ Integrated Res > Apogee Drive II Pump/CPU Block > GPU 1 > GPU 2 > Single Rad > Back to the Triple. I could be wrong but that doesn't sound overly restrictive. Tubing would be 3/4" OD x 1/2" with some Bit Powers angled fittings to cut down on the tubing runs.

 

[GTXJackBauer]

As stated the first picture is serial and the second is in parallel. I would advise serial because if in parallel the liquid will enter the least restrictive path of way. Granted there will be a few degree difference between both GPUs but not at a alarming rate.

 

[m0r7if3r]

As stated the first picture is serial and the second is in parallel. I would advise serial because if in parallel the liquid will enter the least restrictive path of way. Granted there will be a few degree difference between both GPUs but not at a alarming rate.

The liquid will split proportionally (by restriction) between the two paths if the flow is parallel. For identical components, like GPU blocks, parallel flow yeilds slightly better temperatures, I want to say it's because it improves flow in the rest of the loop, but I don't remember. That said, the difference is minor, so it shouldn't be something a system is designed around, but rather a way to see some additional cooling for (mostly) the same gear.

 

[MattMan657]

Here's a thought. If keeping a high pressure is important, wouldn't it make sense to stick with a Serial and turn your pump up a bit to increase the flow to the rate that a Parallel would give?

 

[GTXJackBauer]

The liquid will split proportionally (by restriction) between the two paths if the flow is parallel. For identical components, like GPU blocks, parallel flow yeilds slightly better temperatures, I want to say it's because it improves flow in the rest of the loop, but I don't remember. That said, the difference is minor, so it shouldn't be something a system is designed around, but rather a way to see some additional cooling for (mostly) the same gear.

You made my point by saying it will improve flow in the rest of the loop hense me saying it will enter the least restrictive part of the loop. It will take most of its energy passed the blocks back to the loop. Yes, in parallel you get even temps between GPUs but in serial, correct me if I am wrong, you will get a cooler temp to the first GPU and warmer in the second GPU but not as cool in parallel. I guess since most quality pumps have good pumping power serial is usually the choice to go with. Its up to the OP which he feels more comfortable with but my personal preference would be serial.

 

[m0r7if3r]

I'll let data speak for itself.

http://www.swiftech.com/Resources/White_papers/Actual influence of flow rate on system temp.pdf