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XD3 Orientation


Smokester
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Hello

2 Questions:

1) Can the XD3 be mounted with a 90 Degree offset, such that the OUTLET ports are facing DOWN.

I understand all the documentation states to be mounted upright, and I found several posts that clearly state not to lay horizontally, but nothing about outlet down.  Regardless of whether this is OK or not, could I potentially have some kind of explanation to any side effects of doing it?

2) If there are two pumps in series, do they both require liquid being filled a couple centimetres from top, or only one?

I also have a XD5 for this loop.  I have seen it explicitly stated to NOT fill the XD3 (possibly XD5 as well) completely to the top.  Is this just to leave room for expansion/contraction from heat and/or provide a 'safe' place for air to collect?  The XD3 will be higher in the loop if that makes any difference.

Thank in advance for any information provided 🙂

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A question that may solve your problem entirely : Why two pumps in a single loop? 🙂

Dual pumps are very rarely needed, usually for over the top builds with huge restrictive loops, like workstations with 4+ GPUs and a ton of radiators, or decked up super towers like the 1000D, or the LianLi desk PC.. 

Also, mixing a D5 with a DDC pump is going to be tricky to control to say the least. they have different speed specs and head pressures so you will have fun times balancing them out. 

As for having the XD3 sideways, you'll have more chances to suck air through the pump inlet. It will sit higher in the water. That can damage it with time.. and the XD3 doesn't need that given its tendency to cause early RMA.

If i were you (and if your build is the one in your hardware profile) i'd save the costs of the XD3 and go with a single XD5. 

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Hi @LeDoyen , thanks for response.

Curious, why would outlet at the bottom increase chances of air in system? You mention the inlet being the issue, could you clarify why?   This brings me to my other question I asked above:

2 hours ago, Smokester said:

2) If there are two pumps in series, do they both require liquid being filled a couple centimetres from top, or only one?

Would filling the system through the XD5 and leaving air space in that while removing all air from XD3 solve the issue of air from the inlet?  Would there be any other performance consequences or the more serious reliability issues outlined in laying the XD3 horizontal (creating a vortex I think I read somewhere)?

Manual specifically states mounting vertically  (but nothing about rotations) and the general rule of thumb is for outlet to be below reservoir, so this seemed reasonable. Totally understandable if you don't know for sure.  Was just checking here for some clarity from community or possibly Corsair themselves.

 

Why two pumps? Well, there's plenty of reasons, redundancy and noise are top of the list though. Reducing wear and tear and keeping the XD3 cooler by running slower is a plus, but not a reason. An unintended benefit, figured I could capitalize on higher flow rate of D5 and higher pressure of DDC, however you are implying that is not the case and that I need to "balance" the pumps.  To be clear, the plan was always to run at similar PWM curves.

I am no watercooling expert, and would love to know any theory if I am wrong, but this is my understanding:

So long as both pumps are working under their P-Q curve (or more specifically, their safe operating zone),  and within reasonable pressures (cavitation) of each other, everything is fine and no "balancing" is required when mixing and matching pumps. The pumps will simply add their pressures and the flow rate will adjust to the new P-Q curve

Since pumps in a series will not increase flow rate directly there is no risk of flow rate ever going beyond rated capacities (not to mention flow restrictions).  As for pressure, I have not found Corsair's exact rated maximum operating pressure, but have seen other DDC pumps rated for 1.5 bar (15 metre head)  and D5's for 10 Bar which would both be far beyond any doubling of pressure combining these pumps could do.  Outside of a stress test (which if there are any notable reasons there could  be an issue I would certainly modify it), these pumps would never be running anywhere near full power. 

I welcome any input here.  If there are some serious concerns I am not aware of I'll certainly look into it. Need an excuse to buy a good flow meter anyway 🙂

 

As for why this combination? XD3 came in kit at a pretty substantial discount, but due to noise and reliability complaints out there for the XD3, decided I would prefer an XD5, so grabbed an XD5, later on, also on sale. I am fully aware of the overkill in power but this system will be run nearly 24/7, downtime is not acceptable (hours are OK, days/weeks/months are not) and thus redundancy and noise are crucial. Also, "why not?"

But all off topic, "why" I want to do this isn't really important. Just want to know of any potential issues of mounting in that direction and how to manage air in the pumps.  The air from inlet is interesting and possibly question #2 answers #1?

Thanks for response 🙂

 

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There's no wear to speak of honestly since the impellers are water lubricated, and only spinning around a small ceramic ball. If you use a clear coolant there shouldn't be any significant wear, probably for the lifetime of your PC.

For head pressure, it's usualy just below 500mBar (between 3 and 5m head pressure for D5 and DDC respectively).

I don't know how the XD3 works, but often the Xylem DDC pumps go to max speed at 50% PWM, while the D5 is full speed at 100%. That may be another issue, unless Corsair makes their own controllers and change the PWM response.

If you are going to make a typical loop with one CPU and one GPU, you won't even need to accelerate the pumps. The waterblocks have a minimum required flow below which the temperatures will climb sharply. But once you meet that flow, the block temperature won't change drastically if you increase it.

For example, if you load your GPU with some furmark torture test or an OCCT test, with your pump at say 40% PWM, you may gain 2 or 3° by running the pump at full speed. Higher water flow doesn't mean more cooling. It just means... higher water flow 🙂

A single D5 or DDC is already more than enough for such build. If you need redundancy, it's usually better to go with a dual pump instead of 2 discrete pumps with reservoirs.

You could also just have a spare D5 pump (just the pump module) in case yours bites the dust, but D5 are very reliable, and you can find Xylem pumps in every watercooling store anyway and get it pretty quickly if you didn't want to invest in a spare to keep at home. Actually, DDC pumps are also very reliable, when they are not encased in a cheap plastic enclosure with no airflow 🙂 D5 is watercooled, and DDC is air cooled, which is why i'd rather advise to keep the XD5 if you go single pump.

Custom loop pumps are very dependable. If it doesn't die right away from electronics failures, you know it will last for years.

 

For your question 1, it's not the outlet at the bottom that is the problem but the inlet being raised higher up. The risk of ingesting air will be a lot higher and that's how you damage a watercooling pump. They are probably not powerful enough to cause cavitation but the strong disturbance of passing air will damage the bearing or the impeller.

The outlet has to be below the reservoir if the reservoir and the pump are aligned. With a sideways pump it changes, obviously. The only red lines are to not have the pumps head down, and have the inlet always covered with water. beyond that, it's up to the manufacturer to arrange the ports as they like. The problem with the XD3 is that the reservoir is extremely small so there's not much water above the inlet. by rotating the pump 90° you further decrease that gap. 

#2 i think you won't have a choice. it will be extremely hard to purge all air from the XD3, maybe even impossible. same deal if you wanted to fill the XD5 completely. 

 

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The XD3 has a very specific intake action and altering the angle is going to have a negative impact on performance and noise.  The actual pump inlet is in the center of the reservoir and it has specific guide channels designed to work with gravity.  By turning that side up, you move the vortex action into a place it shouldn't be.

-CX-9040003-WW-Gallery-XD3-RGB-14.png

 

 

 

I don't see any reason to use the XD3 at all in this build unless you don't have space for the XD5, which does not appear to be the case.  You are not gaining anything by running both pumps in tandem.  You are likely to add noise.  DDC pumps don't do quiet all that well.  They are geared like a truck and produce high pressure at low speeds, but it's at 3700 rpm at 50% and I assure you that is loud.  For what you are describing, a XD5 or any D5 pump is what you want.  It can set low and quiet when there is no load.  It is capable of higher throughput at maximum at it will make less noise at 100% than the XD3 does at 50%.  I use a dual DDC and D5 pump combination, but I also am running an open case with dual external 480mm radiators and a solid 1 meter of vertical climb.  Inside a normal case I would have no need for two.  It's the extremely tall nature of the build that makes two pumps worthwhile, as well as the ability to put the DDC below the deck with the other radiator where I can't hear it.  

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@LeDoyen Thanks again for the well written response.

8 hours ago, LeDoyen said:

For head pressure, it's usualy just below 500mBar (between 3 and 5m head pressure for D5 and DDC respectively).

I think this was into my response about max operating pressure.  What I was specifically referring to was the theoretical pressure it could withstand as opposed to what it can pump out... ie working within it's safe limits.  But ya, combining the pumps is well within the limits.

 

8 hours ago, LeDoyen said:

Xylem DDC pumps go to max speed at 50% PWM

You are pretty close in regards to Corsair.  According to Techpowerups review they showed 4711 - 4545 - 3645 RPM for 100%-60%-50% PWM respectively with flow rates and sound very close 50 and 100%.

 

8 hours ago, LeDoyen said:

If you need redundancy, it's usually better to go with a dual pump instead of 2 discrete pumps with reservoirs.

As mentioned, the pumps are purchased.   I have them, can't return them.  I could accept the XD3 as a sunk cost at this point and keep as a backup though.

 

8 hours ago, LeDoyen said:

DDC pumps are also very reliable, when they are not encased in a cheap plastic enclosure with no airflow

With cooling in mind, it is mounted  with an air INTAKE fan directly to it's backside and will be taking coolant intake from the radiators.  I doubt those are going to make huge differences since it's not water cooled and the plastic on the backside is a terrible heat sink but combined with running at 30-40% speed I figured heat shouldn't be an issue or at least minimized as much as possible.

8 hours ago, LeDoyen said:

#2 i think you won't have a choice. it will be extremely hard to purge all air from the XD3, maybe even impossible. same deal if you wanted to fill the XD5 completely. 

I assumed if only the XD5 was running during fill process it would be similar to removing air from rad.  Guess I'll find out if I do indeed move forward with build, even if it's in the normal vertical position.

7 hours ago, c-attack said:

The actual pump inlet is in the center of the reservoir and it has specific guide channels designed to work with gravity. 

@c-attack Thanks for response.  This makes sense and I think ultimately answers the question. 

 

7 hours ago, c-attack said:

I don't see any reason to use the XD3 at all in this build unless you don't have space for the XD5, which does not appear to be the case.  You are not gaining anything by running both pumps in tandem.  You are likely to add noise.  DDC pumps don't do quiet all that well.  They are geared like a truck and produce high pressure at low speeds, but it's at 3700 rpm at 50% and I assure you that is loud. 

The question of need, was never a question.  As  mentioned, I bought the kit including the XD3 at a significant discount and decided I would prefer an XD5,  Waited for a sale and bought that as well.  I now have both pumps and neither can be returned.  I have them and want to use them.  As stated to Ledoyen, I could accept the XD3 as a sunk cost for getting such a good deal on the  kit, but more so just want to make it work if I can.  The goal was to run XD3 at 30-40% speed at the significantly lower RPM's /noise levels of 50%+ with the same planned for the XD5 and seeing how temps compare to increasing RPM's  and introducing noise.

 

Question 2 is still unresolved here though:

On 11/22/2022 at 1:14 PM, Smokester said:

2) If there are two pumps in series, do they both require liquid being filled a couple centimetres from top, or only one?

Is this just to provide space for heat expansion/contraction and if so, is it only necessary in one pump?

 

Lastly I should note. I don't live in the States. Finding watercooling parts is not as easy as going to Micro Centre or Amazon.  My choices are far more limited and unless I want unreviewed Chinese brands, I have to either order directly from EK with significant increases in costs, shipping and shipping delays or something similar.  Corsair on the other hand services my market well and is  priced appropriately.  So the act of 'just get another if one fails' isn't something I can necessarily bank on, and thus redundancy is highly desirable.

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depending where you live, Aquatuning could be a retailer to consider for spare parts.

The thing is, with those two very different pumps, you may introduce more problems trying to solve a nonexisting issue. Keeping the XD3 as backup is pretty viable.

you may not even need to run the XD5 past 50% PWM to be honest. and that one could take runing at full speed all year long, they are sturdy AF.

The only failures i see on the forum related to XD5 are people disconnecting/reconnecting the PWM cable while the pump is powered up.. mostly user errors.

Either way, if any of the two pumps die, you'll have to purge the loop to take it out, so you might as well only use one at a time.

As for the air in the reservoir, you want to have some for expansion yes.  Now, it's not a car radiator. you may have 15 - 20° between coldest and hottest, but it's not a good idea to test how high the pressure can get before it leaks 😛

Besides, it's nice to see some water movement in the res 🙂

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28 minutes ago, Smokester said:

You are pretty close in regards to Corsair.  According to Techpowerups review they showed 4711 - 4545 - 3645 RPM for 100%-60%-50% PWM respectively with flow rates and sound very close 50 and 100%.

 

That was for the XD5?

DDC usually don't go above 2200 RPM (4400 on the reading) and D5 up to 2400 RPM (4800 on the reading).

What i saw was that D5 get to 4800 at 100% PWM, while DDCs go to 4400 at 50% PWM (the 50 to 100% range do nothing, the pump is already running at full blast). If the XD3 behaves like a Xylem, and you run both pumps at 50%, you'll have a XD3 at full speed and a XD5 close to half speed

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So on the fill you will disconnect either the XD5 or XD3 from it's power.  Fill the system normally like you have one pump.  I would choose the XD5 as the working fill pump in most all circumstances because of the larger reservoir and easier fill.  The liquid will pass through the XD3 and once it starts freely circulating the entire loop, flip the PSU back off and hook the XD3 back to molex.  Now power up with zero chance of the XD3 running dry.  The XD5 at maximum with the PWM/tach wire disconnected should have no trouble filling things up on its own.

 

On a side note, you might consider leaving the XD3 PWM/tach connector on any MB or Commander fan header so it will not run 100% at max during the fill process.  That thing hits pretty hard when it turns on and may make things a bit frothy.  Once you are up and in the OS with CUE, you can play around with both pump speeds including maxing both out to power out any air pockets.  This will be a more controlled procedure with exact speed settings available.  Over the years there have been a few funny user stories about terrified cats, wives, and thrown screwdrivers when the XD3 kicked on the first time.  

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3 hours ago, LeDoyen said:

That was for the XD5?

XD3.  Guess he going off the reading if reading is different than actual for some reason.  Regardless, was just saying his data for the XD3 compares with what you  were saying. Although in his sample, the drop off appears to be below 60%, I'm sure there's going to be variance between pumps/tops/testing methods.

https://www.techpowerup.com/review/corsair-hydro-x-series-xd3-pump-reservoir-combo/5.html

4 hours ago, LeDoyen said:

What i saw was that D5 get to 4800 at 100% PWM, while DDCs go to 4400 at 50% PWM (the 50 to 100% range do nothing, the pump is already running at full blast). If the XD3 behaves like a Xylem, and you run both pumps at 50%, you'll have a XD3 at full speed and a XD5 close to half speed

Ya I'll certainly have to fool around with it when I get there.  That was why plan was to run DDC @ 30-40%, because I had seen that behaviour from the review  I just linked above.  I can easily adjust both pumps to run at their maximum inaudible speeds for most uses and only increase more if I can see any discernible impact in temperature under load.  My very basic napkin math figured I would get about 1 gpm running both in that scenario, so I'm not expecting much benefit going louder, but that's the point of testing.

4 hours ago, LeDoyen said:

Either way, if any of the two pumps die, you'll have to purge the loop to take it out, so you might as well only use one at a time.

Yes but the key element here is the system will keep running (albeit hotter and would need to adjust speed of working pump to compensate) and could be done at leisure instead of shutting down the middle of doing something important.  But agreed, a failed pump would need to be removed.

4 hours ago, LeDoyen said:

As for the air in the reservoir, you want to have some for expansion yes.  Now, it's not a car radiator. you may have 15 - 20° between coldest and hottest, but it's not a good idea to test how high the pressure can get before it leaks

Absolutely agree! Just wanted to know/confirm the theory.  I'm now curious if I'll be able to keep air in both if I'm only filling with XD5. Guess I'll find out, but by the sounds of it, as long as one has air space, should be fine.  If I can leave some space in DDC (D5 WILL have air space, filling with that) I will though.

 

@c-attack Thanks, yes using the XD5 for filling is the plan 🙂 .  Will only hook up the molex and mobo jumper to psu while filling the loop, and not the commander pro or anything else related to the PC. My only concern was whether both pumps should be given air space at top or if only one needed air that space. Commander pro and everything else connected to PC will come after leak testing.

4 hours ago, c-attack said:

Once you are up and in the OS with CUE, you can play around with both pump speeds including maxing both out to power out any air pockets.  This will be a more controlled procedure with exact speed settings available. 

Yup that's the plan. Although I will fire up the XD3 at 100% during the leak testing.  I'll be sure to turn off the PSU before switching any cables.

4 hours ago, c-attack said:

Over the years there have been a few funny user stories about terrified cats, wives, and thrown screwdrivers when the XD3 kicked on the first time.  

Looking forward to that 🙂

 

All in all, I have both pumps installed so I will be using them.  Through the testing if I do find the DDC to be completely useless or increasing noise to levels higher than with the D5 alone, I do have option of removing it as you guys suggest.  Given the sunk costs, might as well see if lower noise can be achieved for similar performance by running both at lower speeds.  I'll post some temps of each pump at various RPM's both together and individually when I'm all done in case curious.

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