Recommend me some new pumps and disconnects

Teenyman45

2[H]4U
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Nov 29, 2010
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I had been using the same two pumps since my very first water cooling project, a pair of Swiftech MCP35x's working in serial, which had always been more than sufficient to easily pump a nearly gallon's worth of in-system water (lots of thermal mass!) through 6+ feet of tubing into two 480, 80mm thick rads + a 120rad + a cpu block + as many as three GPU blocks. Outside of stress testing, the pumps were almost never run full out, as the baseline power management set the speed about 10-15% over stall most of the time.

Unfortunately, one of those pumps reach its end, with the impeller making an odd clicking noise once every few seconds but not actually spinning any longer. I don't feel comfortable with just one pump.

What are some of the better fully assembled pumps, excluding pump res combos? Can I mix a D5 with my remaining DDC, or should I retire the MCP35x outright?

Previously, I had used Tygon tubing (10mm inner / 13mm outer) and in the present re-build post-pump-removal am using lab grade silicone tubing of the same diameter (I don't care that it's halfway opaque rather than clear... the tygon discolored, even the unused stuff in a cardboard box after enough years). I don't believe this should impact pump selection, but I'm mentioning it just in case.

Separately, I have never used quick disconnects before, but since it looks like I'll be tearing down a rebuilding a loop multiple times what are some good QDC (full parts list) that would work with my narrow tubing and compression fittings?
 
I don't see why you couldn't mix pumps in series, but I'd be inclined to keep them the same just for the sake of uniformity.

That said I currently have three pumps in my loop (all of them EK D5 PWM Gen 2) in two separate loops. Two of them are in series.

I am starting to move away from the concept of putting pumps in series.

When you do, you only get a very small increase in flow over a single pump. It helps, but the increase is small (10-20%) and you are paying for it by dumping more heat into your loop (or with DDC pumps into the air in your case).

I already have two loops sharing the same res in my build, with the fluid mixing and equalizing the temps in the res.

When I have some spare time (which may be never at this point) my future plan is to split things up further and have three separate loops with one pump each, all mixing in the reservoir.

It seems much like building a race car. You benefit much more from reducing weight than you do from increasing engine power. Using the pumps in single loops with less resistance buys you better flow (or lower quieter pump speeds) than running them in series with a greater loop resistance.



Right now I have them as follows:

Loop 1:
Blocks only. Res -> pump -> GPU -> CPU -> Res

Loop2:
Res -> Two pumps in series -> three radiators one in series, two in parallel -> res.

Future state:
Loop 1 stays unchanged

Loop2 gets split in two, with a couple of new radiators, each identical as follows:

Loops 2-3:
Res -> Pump -> Two rads in series -> Res


My expectations are that I will maintain much better flow rates, and be able to keep the pumps slower (and quieter) longer.

As for which pumps to get? I mean, All D5's are more or less the same, all DDC's are more or less the same, right?

I randomly wound up with the EK D5 G2 PWM's just because they happened to be in stock when I was shopping, but I have been happy with them.
 
I don't want to mess with making sure the pump seals are perfect or that I've aligned the spinning bit just right (or wrong), so the tops on pre-assembled units can matter, just as some pump cases can also act as heat sinks. I'd buy another mcp35x, but Swiftech doesn't really seem to be around anymore despite the webpage technically being active.

Then intention is more for reliability, with the surviving pump having made it about 9 years and counting and then secondarily for pump efficiency. As indicated in my initial post, I'm not looking for maximized flow rates because previously the pair of pumps ran not much faster than the stall speed. Besides, rather than using 3/4th of an inch or inch wide tubing, I'm using narrow tubing (though that does create enough surface area to radiate a reasonable amount of heat on it's own) and heat being trapped in the case is not a problem because I'm using a TH-10 with 7 intake fans (using those old silverstone 120mm fitted filters) and 9 exhaust fans. I'll also probably re-install a dedicated fan to blow on the GPU's power delivery circuitry.
The loop is robust enough that with my exhaust fans (early Noctua F series) running at about half-speed I don't even need a pump to keep GPU temperatures under control so long as I'm not actively gaming... which I found out the hard way when doing some outside-outside-of-the-case work and the pump was apparently not hooked up to its molex connector for an unknown number of hours.
 
I don't want to mess with making sure the pump seals are perfect or that I've aligned the spinning bit just right (or wrong).

I felt the same way when I started, but I have done three of them now, and they all just worked. I didn't do anything special to align them, just installed the provided O-Ring that came with the pump top kit, and hand tightened them. Et voilà.

I can understand being hesitant, but it is really fairly simple.

I'd buy another mcp35x, but Swiftech doesn't really seem to be around anymore despite the webpage technically being active.

Oh damn, I sure hope that isn't the case. What gives you that idea, if the site is up?

Separately, I have never used quick disconnects before, but since it looks like I'll be tearing down a rebuilding a loop multiple times what are some good QDC (full parts list) that would work with my narrow tubing and compression fittings?

Forgot to answer this one in my first post, but I have had very good luck with Koolance QD3's They have just been perfect for me.

These are the same ones Kyle used in his test setup, and he spoke very highly of them as well.

A absolutely tiny amount of fluid comes out when you disconnect them. I usually wrap with paper towels while pulling them just in case, but you probably wouldn't have to, its so little.

The part numbers can be a little bit confusing, but what it really comes down to is that for each connection you need two, one male and one female side.

QD2's (smallest size) fit with QD2's, QD3's (mid size, most common) fit with QD3's and QD4's (largest size) fit with QD4's. You can't mix the different sizes.

They offer a large variety of backs on the QDC's. Everything from G1/4 threads to included compression fittings, barb fittings etc. of various sizes. They also come in black and silver (and possibly other colors, not sure) The QD3 models are the most popular, and as such are offered with the most varieties of backs.

You can always just get the GPT threaded ones and add your own fittings to them if you want, but the ones with the built in fittings have the benefit of being a little shorter, so if space is a concern, I'd go with the ones that have the built in fitting type of your choosing.

I've personally have all of the following ones in my build right now:

- Black Male QD3 with 3/8ID, 1/2OD compression fitting back. (attaches directly to my tubing, no additional fitting needed)
- Black Female QD3 with 3/8ID, 1/2OD compression fitting back. (attaches directly to my tubing, no additional fitting needed)
- Black Male QD3 with male threaded G1/4 back (I screwed these straight into my CPU and GPU blocks)
- Black Female QD3 with male threaded G1/4 back (I screwed these straight into my CPU and GPU blocks)
 
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Swiftech is still around, I bought some stuff from them last year.
 
Swiftech is still around, I bought some stuff from them last year.

It looks like their TLS cert on their website is expired.

I also just looked at their social media. Their Facebook page hasn't had a post since 2019.

Last tweet was also in 2019.

Doesn't necessarily have to mean anything, but...
 
Ppcs has the dual top mcp35x but the single pump is oos and has been for quite a while.
Koolance QDCs are the only kind I've ever used so i dont have alot of experience but I've never had any issues.
 
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