Using 3/8" tubing on secondary loop...

Hey, I've been around here long enough to know that 3/8" tubing will hurt flow measurably and therefore increase temps, but hear me out on this...

On my new rig, I'm going to run a loop dedicated for the CPU. I'll use 7/16" on this loop for sure. In fact, on my bench setup, I'm already using this loop to stabilize my overclock with good success.

http://members.shaw.ca/virtualrain/rainmakerwc8.jpg

When I'm done on the bench, the other loop will cool the Digital PWM, the NB, SB, GPU (8800GTX with EK FC block), and my water cooled PSU. The main intent of the second loop is to eliminate noise while providing enough cooling to maintain overclocks. I don't need record temps... I just need "enough" cooling.

Question is, will a separate loop with a DDC Ultra, PA-120.2 and the above mentioned blocks likely have enough cooling capacity to beat air cooling even with 3/8" tubing?

The thing is, I'm meeting my stable OC objectives with good air cooling on these components on the bench now, so I'm assuming (hopefully correctly) that when I switch to water, even with 3/8" tubing on the secondary loop, it will be better than the air cooling I'm using now.

Why not just use 7/16" all around?... I could do that and may still, but if I go with 3/8" tubing, I can use some much more attractive compression fittings instead of ugly barbs. I can't use compression fittings with 7/16 or 1/2 because the locking rings will interfer with each other because the fittings will be too close together on most of these small secondary blocks. It will also be somewhat tidier and less cluttered looking loop with slightly smaller tubing.

The bottom line is, can I exchange a bit of cooling performance for some cosmetic improvements without actually loosing any system performance?

Bleh 3/8" tubes won't hurt flow so much air will beat it :p: (far from that) A DDC2 with Petra's top is one beast of a pump...

I use 3/8" on my whole setup and I'm not hurtin' too bad........

virtualrain, I swear you are wrestling with all of the very same issues I've fought with, from compression fittings (I prefer them to barbs as well) to braided/sleeved/hard tubing to block material (delrin versus uniform white metal). I'm seeing the exact same dilemmas I've struggled with, function versus form.

I think you've already taken the best approach which is to first determine what level of performance you wish to achieve and maintain from the electrical components in your system. From there you can determine if you need to pursue a 1/2" tube solution or if 3/8' will allow you to achieve your goals.

Have you already tested which compression fittings will work with your chosen chipset blocks? I could be wrong (as I only tested 1/2" fittings), but I believe that even 3/8" fittings have problems with Swiftech's delrin blocks due to the o-ring channel, preventing the threads from reaching deeply enough to get a solid bite.

Hey, I'm glad I'm not alone! Trying to do something a bit different that looks cool without sacrificing performance is tough! :D

I'm going with alphacool blocks on the NB/SB which have decent spacing between the G1/4 taps and have a nice nickel finish on them. Then I'm going with an EK Full-cover block on the GPU and I'll be using one top and one bottom port on that, so all should be good with respect to using compression fittings. At any rate, I'll get my hands on some 3/8" compression fittings when I get my blocks to make sure.

Difference between 3/8" ID and 1/2" ID in reality to the enduser is next to bugger all - for most it's unnoticeable. Know plenty who have moved from 3/8 to 1/2 and vice versa who have noticed no change whatsoever.

Note - the 3/8" tubing that supports compression fittings tends to be 3/8" OD (8mm ID 10mm OD) and is generally fairly prone to kinking due to the 1mm wall thickness... unless you've managed to find some 3/8" ID 5/8" OD compression fittings to allow you to use the common Tygon or Clearflex 3/8" ID hose that most places sell... which leads on to...

Note2 - OD of 3/8" tygon / clearflex and 7/16" Masterkleer is the same for reference... so if using 5/8" OD compression fittings on 3/8", the space consumed on the block / closeness of fittings is irrelevant as the tubing OD is the same.

Thanks Marci... I was planning on using the Koolance compression fittings for 3/8" as they also have some matching 1/2" fittings I can use on my CPU loop. The 1/2" fittings are designed for 1/2" ID and 3/4" OD and are way to big to use on most blocks without the locking rings interferring... which is why I want to go with the 3/8" on the secondary loop.

Looking at the tubing that Koolance sells, it appears it is 3/8 ID and 14mm (0.55inch) OD so it would have 2mm walls. I guess I may have to buy their tubing as this sounds like odd specs. Does anyone else make tubing with those wall specs?

Sidewinder sells Tygon and a stuff called Durelene, which I have, it's stiffer but much more suited for compressions, in the size necessary. I use 3/8" compressions throughout and I'm perfectly satisfied. My temps are just what I ask of them, and that's all I care about-and it's almost dead silent...

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Originally Posted by virtualrain

Thanks Marci... I was planning on using the Koolance compression fittings for 3/8" as they also have some matching 1/2" fittings I can use on my CPU loop. The 1/2" fittings are designed for 1/2" ID and 3/4" OD and are way to big to use on most blocks without the locking rings interferring... which is why I want to go with the 3/8" on the secondary loop.

Looking at the tubing that Koolance sells, it appears it is 3/8 ID and 14mm (0.55inch) OD so it would have 2mm walls. I guess I may have to buy their tubing as this sounds like odd specs. Does anyone else make tubing with those wall specs?

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Link for 1/2" compression fittings PLEASE?! :)

EDIT: Google is my friend. Do you mean these: 1/2" fittings. Any idea what the max OD you can use with these is?

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Originally Posted by Cyprio

Link for 1/2" compression fittings PLEASE?! :)

EDIT: Google is my friend. Do you mean these: 1/2" fittings. Any idea what the max OD you can use with these is?

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Yeah, I have a pair of these I got to evaluate their suitability... They aren't ideal as I think they are desgned for 1/2" ID and 5/8" OD thin wall tubing (the compression ring has an ID of 0.64"). I tried some Masterclear on it and the walls are to0 thick to allow the compression ring to get more than a half-turn on the fitting. I plan to use 7/16" tubing with these anyway but I'm going to have to dremel out some of the ID on the tubing to get them to fit well as I don't want to go with thin wall tubing.

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Originally Posted by virtualrain

Yeah, I have a pair of these I got to evaluate their suitability... They aren't ideal as I think they are desgned for 1/2" ID and 5/8" OD thin wall tubing (the compression ring has an ID of 0.64"). I tried some Masterclear on it and the walls are to0 thick to allow the compression ring to get more than a half-turn on the fitting. I plan to use 7/16" tubing with these anyway but I'm going to have to dremel out some of the ID on the tubing to get them to fit well as I don't want to go with thin wall tubing.

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Cool! So they should work fine with 7/16” ID , 5/8” OD Tygon. :up:
Now i just need to see if anyone stocks them in the UK - or get them shipped from Frozen CPU.

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Originally Posted by Cyprio

Cool! So they should work fine with 7/16” ID , 5/8” OD Tygon. :up:
Now i just need to see if anyone stocks them in the UK - or get them shipped from Frozen CPU.

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They won't work fine with 7/16" and 5/8" tubing as the wall is too thick... you will need to dremel out the end of the tube to make it thinner as I said.

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Originally Posted by virtualrain

They won't work fine with 7/16" and 5/8" tubing as the wall is too thick... you will need to dremel out the end of the tube to make it thinner as I said.

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But the tubing is .625" and the ID of the ring is 0.64". You mean as the 7/16" needs squeezing to get over the nozzle the Tygon's OD becomes larger than .64"?

Is it possible to just dremel the ring nut?

No, it's not that... once the tubing is over the barb, it's difficult (but not impossible) to get the ring over as the threads inside the ring can't get past the large diameter of the tube over barb. The main problem is that although the ring is designed for 5/8" it won't tighten down more than half a turn if the tubing wall is too thick as is the case with 7/16" ID 5/8" OD tubing.

You could dremel the ring out I suppose, but it would look worse and be more effort than just carving a bit of tubing out of the inside in my opinion.

Ok, i think i get it now. Thank for explaining again to a dimwit. :)

Doesnt look it matters though as i cant find a UK re-seller and it would cost me $80 to get 3 sets from Frozen CPU shipped to London. :eek: :mad:

Hey I just tested the koolance compression fittings for 3/8 ID 1/2 OD tubing on the Apogee GT, MCW60, and MCW30. They all were an extremely close fit, but nonetheless they work. You have to get them on in sort of a special way though sometimes and for the MCW60 you need to remove the retaining bracket first and put it back on after screwing in the compression fittings. If you need any help or screenshots just pm me.

dude you have to get off that big tubing high horse...

3/8" tubing is the BEST..

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Originally Posted by Aldy402

dude you have to get off that big tubing high horse...

3/8" tubing is the BEST..

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Yep, I have 3/8in tubing in my loop, it's excellent and to looks way cleaner than that fatty 1/2in. tubing.:rolleyes:

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Originally Posted by Aldy402

dude you have to get off that big tubing high horse...

3/8" tubing is the BEST..

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meh.. too skinny looking to me. 1/2" is too fat too. 7/16" is like perfect though :cool:

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Originally Posted by SparkyJJO

meh.. too skinny looking to me. 1/2" is too fat too. 7/16" is like perfect though :cool:

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I'm really digging the look of my new loop with 7/16 masterkleer. not too fat, not too skinny :)

I decided to use 3/8 inch tubing for my second loop (NB/SB/mosfets only) ... but the original 3/8 tygon I ordered was 5/8 OD ... so it was the same OD as my 7/16 tubing and wasn't "smaller." I then ordered some 3/8 ID tubing with 1/2 OD ... but it was too flexible and wouldn't "hold the loop" so I ended up with the 3/8 ID, 5/8 OD tubing ... works fine (stayed with 3/8 ID, since I'd already ordered the fittings).

( I realize this isn't all that relevant to the OP's goal with compression fittings, but thought I'd post it for others new to this whole thing ... make sure you check ID and OD on tubing )

I also use all 3/8" ID (5/8"OD) for all my tubing runs. When you have two MOSFETs and two MCW-30s along with the CPU and EK-FC800 block, you need tight radius tubing. I like the silicone tubing as it is much softer.

May not be as good as 7/16" or 1/2", but the pressure drop from the tubing is nothing compared to that of a Storm waterblock.

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Originally Posted by Marci

Difference between 3/8" ID and 1/2" ID in reality to the enduser is next to bugger all - for most it's unnoticeable. Know plenty who have moved from 3/8 to 1/2 and vice versa who have noticed no change whatsoever.

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Thanks for your opinion on that! I was glad to hear it.

Makes me feel better about my 3/8" section, that I am using to cool the Maximus SE stock NB block, in my otherwise 1/2" loop.

No big deal then.... :up:

If im lucky, it may act as a D-tek nozzle of sorts, jetting the water into the NB block a bit faster, as the hose size constricts a tad.