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1/2 or 3/8?

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Catalan

Member
Joined
Aug 11, 2004
Location
Las Vegas, NV
Is there any reason to go with one over the other? I've read a review that the MCW6000 cools better than the MCW6002.
 
Your right, plus 3/8" tubing is much easier to handle and looks better (my opinion).


Jon
 
I was having similar thoughts after looking at the 2 cooling abilities of these blocks at:
http://www.procooling.com/html/pro_testing.php

The 6000 seems to best the 6002 by a degree or so at high flow rates. Assuming the internals are the same and the only difference is inlet size, it is hard to understand why that should be.
 
If this is true will 3/8" tubing fit on the Swiftech MCP650 because their site says it made for 1/2" tubing
 
I dont know if 3/8 will fit, I think the barbs are actually 5/8 for maximum flow. at least thats what the mcp600 was. The reason the performance is higher is because of the increased velocity of the waterflow.

Jon
 
Catalan said:
If this is true will 3/8" tubing fit on the Swiftech MCP650 because their site says it made for 1/2" tubing

Tried it...nope, sorry, no way in hell with the outer edges.
 
All you do is buy 1/2" ID to 3/8" ID nylon adapters. Of course, make sure you use 1/8" walled tubing if you're going to go with 3/8" ID. The MCP650 is similar to the Mag3 I have, in terms of power, and may collapse the tubing if the sidewalls are too thin (1/16") like it did to my Tygon R-3603. I'm switching to 1/8" sidewalled Clearflex now.
 
I've stretched 5/8" tygon over 3/4" barbs, same size difference. It's doable but it's a pain, you have to boil the tubing and really struggle to get it on. Least you know it's not coming off! If I were to do a 3/8" ID system I'd definitely get 1/2" barbs and stretch over em.

As to whether you should get 3/8 or 1/2, it depends on you system. A weak pump will see a flow rate increase from the larger tubing, while a strong one will not.
 
I've stretched 5/8" tygon over 3/4" barbs, same size difference. It's doable but it's a pain, you have to boil the tubing and really struggle to get it on. Least you know it's not coming off! If I were to do a 3/8" ID system I'd definitely get 1/2" barbs and stretch over em.
That's what I do and would do with the 3/8" ID as well. I'm trying to get as close as I can do a true 1/2" ID with the setup I have here, though that's impossible with most waterblocks. I have quite a few sections of 5/8" ID, in fact. I do have some 3/8" ID tubing in parallel though, and it's ever so easy to manage. A true 3/8" ID system is pretty doable, and you'd see some good results from it.
 
I've used both and they seem nearly the same. Just stay away from 3/8' barbs, unless you have no choice.

All you do is buy 1/2" ID to 3/8" ID nylon adapters.
Go with a 1/2"x1/2" splice instead. The 3/8" tubing should fit over the 1/2" barb and use a very short piece of 1/2" tubing to connect the barb fitting to the pump. This way you won't suffer from a restriction. Home Depot has the 1/2" x 1/2"barb fitting.

I've stretched 5/8" tygon over 3/4" barbs, same size difference.
Same size difference but 5/8” tubing has a larger circumference...meaning there’s more material available to stretch. Not so with a 3/8" tube.
 
I have been investigating the use of 7/16" ID (5/8" OD) Tygon R-3603 tubing as a cross-over between 3/8" and 1/2" ID.

In terms of pressure-drop vs length, 3/8" tubing becomes significantly restrictive for the sorts of pumps that we use when targetting above 5LPM flow rates. If you don't really expect to be seeing much above 5LPM flow rates (due to the pump's characteristics coupled with the blocks/radiators in the system), then 3/8" ID tubing is just fine to use, and the performance difference between 3/8" ID and something larger would really be quite negligable.

For the higher flow blocks that really like >5LPM flow rates to strut their stuff, something bigger than 3/8" ID pretty much becomes a necessity (unless you grab a high pressure pump but then you're just fighting the problem with brute force).

The most commonly available choice is 1/2" ID. 1/2" tubing is great for high flow applications, but it is as we know rather large and heavy, and somewhat difficult to turn corners unless it has a fairly thick walls, also making it even larger and heavier. Basically the most useful 1/2" ID tubing is with 1/8" walls making for a 3/4" OD, or something that's pretty bulky. A 1/2" ID tubing setup is good for around 13LPM or so flow-rates before thinking about needing to go to something even bigger. 13LPM though is ~3.5GPM and no one will be seeing flow rates even remotely that high with today's modern moderate-high restriction blocks.

So there has to be a middle ground, and 7/16" happens to be it, and using it by stretching it over 1/2" OD barbs. This creates a nice interface between the ID of the tubing and the ID of the barbs, with there being less of a transitional ID change than what occurs with 1/2" ID tubing over 1/2" OD barbs. What this means is that at the barbs there is actually less pressure drop occurring as the water is pushed through the barb's opening with 7/16" ID tubing than there is with 1/2" ID tubing. So while the slightly smaller ID of the 7/16" ID tubing makes it more restrictive than 1/2" ID tubing, much of this loss is made up by gaining at the tubing/barb interfaces. I calculated that in a system with 1/2" OD barbs and 7' of tubing that using 7/16" ID tubing offers about the same level of pressure-drop as would using 1/2" ID tubing. For much larger tubing lengths (>10') then the game is clearly won by 1/2" ID tubing. For <5' total tubing lengths 7/16" ID tubing wins out fairly easily. For anything up to 10LPM, 7/16" ID tubing is perfectly adequate before possibly thinking about going to 1/2" ID tubing. That's around 2.7gpm, which is still way higher than the flow rates you'll ever see in a real-world system with modern blocks.

Being of a smaller ID, we can get away with using a smaller wall thickness, and instead of using 1/8" wall thickness like we need on 1/2" ID, it is possible to use 3/32" wall thickness with the 7/16" ID tubing (total of 5/8" OD) with just as much flexibility, but with a whole lot less weight and bulk.

I will be redoing my systems in 7/16" ID (5/8" OD) Tygon R-3603 as soon as I find the time to order some in.
 
Last edited:
the MCW6000 cools better than the MCW6002
That is a sensitive subject....yes, the 6000 performs better than the 6002 at the same flowrate,
however the 1/2 tubing will alllow for a slightly higher flowrate, so the two graphs really shouldnt be compared bit for bit, but rather at different points... where this puts the 6002 vs the 6000 is a question still unanswered AFAIK.
To be considered is the different tapered nozzle designs between the two blocks (or actually the lack of a tapered nozzle in the 6000 version).
Overall, 3/8 IS easier to route and manage, but is only advisable in conjunction with the appropriate components.

SenC.
 
I have been investigating the use of 7/16" ID (5/8" OD) Tygon R-3603 tubing as a cross-over between 3/8" and 1/2" ID.

Interesting suggestion - makes a lot of sense actually. Is this size hard to find I wonder?
 
I'm currently asking myself teh same question about what to order this week.
What i plan on getting:
Pump: Swiftech MCP650
CPU Block: MCW6000 or 6002 (depending on ID hose)
GPU block: MCW50 or Maze4 (depending on hose ID)
Rad: BIpro most likely.

Here is my take on the matter:

Hose ID wont matter at all if you've still got a block that uses 3/8 ID barbs, since the water can still only go so fast thru there, thus creating a bottleneck. So if i want to use 1/2 ID i need to use all parts that take advantage of 1/2 fittings/barbs right?
 
legendosiris,

None of the blocks you list require "high" flow rates to perform well, so I'd suggest 3/8ID to make routing easier. 3/8 thick-wall tubing would be a match for the 3/8ID of most 1/2OD barbs; it just requires a little streching. 7/16ID 5/8OD might be a better choice since it'd have to strech less.
 
so essentially, there is no need for me to think about getting the mcw6002 block over the 6000?...

still learning alot..this forum sure is alot of help :D
 
legendosiris said:
so essentially, there is no need for me to think about getting the mcw6002 block over the 6000?...

still learning alot..this forum sure is alot of help :D

From a performance perspective, there is no practical difference.

Buy the one that matches your tubing size the best. If you aren't sure about tubing, buy the MCW6002 and strech the tubing over the barbs (if required).

Tubing should never fit loosely on a barb. Even using a good hoseclamp, the chances of a leak are high when, as an example, using 1/2ID tubing over 3/8OD barbs (MCW6000).
 
gungeek said:
mcmaster has it in the Masterkleer tubing: product 5233K44
25 feet minimum, $0.36/foot

www.mcmaster.com
There isn't a 25 foot minimum purchase for that tubing. I've checked before and rechecked just now and I'm pretty sure you can buy it by the foot as well. At least it lets you add 1 foot of it to your order so I'm assuming it'll work. Just thought I'd clear that up in case anyone was considering buying some. This is what the sidebar says about it too.......
5233K44
Masterkleer General Purpose Clear PVC Tubing 7/16" ID, 5/8" OD, 3/32" Wall Thickness
In stock
Quantity Per Ft.
1-99 Ft. $0.36
100 or more 0.28
 
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