Koolance PMP-450S (D5 STRONG) Pump

Posted: March 5, 2011 in Pumps
Tags: , , , , , ,

We have a new “King of Pumping Power” quiet pump, the PMP-450S.  While the PMP-400 pumps are more electrically efficient (Less Heat Dump), they are no longer also king of power with a top.  The Koolance PMP-450S pumps when run at higher than average voltage 16-24V is simply turning at a much higher RPM and producing more pumping power.  This review will explore this pump in more detail and consider the various differences and requirements of the Koolance PMP-450S “STRONG!”.

I would like to give special thanks to Tim from Koolance for sponsoring this powerful pump:



The pump comes in a factory box as a “Bare Pump” type product.  So while you’re not paying for accessories you may or may not use, you are very much getting a bare pump…nothing more.  It does come wired with a four pin molex to feed the pump and a blue RPM sensing wire, but nothing more.  Don’t expect a manual or base decoupler or clamps or any screws…it’s a bare pump.  This is good for keeping costs down, but you’ll need to plan out purchase of any accessories separately. Fortunately the pump does come with 1/2″ barbs, so there is no need to change out the top to use larger diameter tubing.


No Speed Dial (Voltage Control Only)

Notice the lack of any speed controller, the only control of speed is via voltage regulation which I’ll get into more of below.

Easy to take apart with the factory decoupling ring gives full access in just a minute

There are a couple of important features to point out here on the internals.  The metal cup stainless housing is an improvement over the PMP-400 series pumps for a couple of reasons.  The metal material is better at transferring heat to keep the pump motor (water-cooled).  This could be looked at negatively from a loop heat standpoint, however this is also a positive for keeping the motor cool.  No need to worry about the pump overheating with this metal cup design, it’s essentially acting as a water block of sorts keeping that motor nice and cool.   In addition the metal cup design is superior to the PMP-400 series pumps in regard to PCB leak protection.  In the event of a leak on this pump, water will run down the metal cup and retention ring, and drip to the metal base essentially protecting the valuable PCB and electronics inside.   These are fairly important features that protect this pump from water and heat related damage and probably why you rarely see any incidents of failures.

The other improvement over the PMP-400 series pump is the easy and quick pump coupler.  No need to find just the right torx head or screwdriver…there are no tools necessary to take these pumps apart and they are also extremely easy to put back together.

Downward Spiral Volute with elbow at the exit

The volute design is actually very good.  While there is an “elbow” at the outlet, the outlet is much less critical than the inlet since it doesn’t impact how the impeller is loaded. Generally the factory top is very good and you will see very little if any gains from after market tops.  These pumps also feature a downward spiral volute instead of your typical perimeter spiral.  This seems to be effective just the same, as long as you’re providing additional volume throughout the circumference, the pump is efficient.

Cermaic Ball Bearing

As with all of the PMP-400, 450, 450s pumps, this one too has the highly desirable ceramic ball bearing construction.  I have yet to see one wear out when properly used.  This little ceramic ball bearing is the only wearing part on the entire pump and works exceptionally well in proper wet conditions.  I’ve personally run the similar PMP-450 pumps for many years in plain distilled water without any sort of lubricating additive and have never had an issue, they are by far what comes to mind when I think “Pump Reliability”.  Just be careful not to run the pump dry and it will serve you for a very very long time.

Size PMP-450S vs PMP-400 Modified

Another consideration and often a reason some prefer the PMP-400 series pumps is size.  The PMP-450 and PMP-450S pumps are bigger in stock trim than the PMP-400.  However, I have found that many times once you have modified a PMP-400 series pump to provide additional cooling and the added extra thick top, that it too increases in size.  The PMP-450S is approximately 4-1/4″ tall by about 3-1/2″ wide/long, so it’s not a tiny pump by any means and does take up some real estate in stock trim.  Fortunately we also have bay reservoir options such as the Koolance RP-452×2 or 402×2 which can hold one or two of any of these pumps in a double bay.  Regardless here is a quick comparison of the PMP-450S in stock form compared to a lifted and modified top PMP-400.  The PMP-400 is slightly smaller, but not significantly so.


PMP-450S (Stock Top) vs PMP-400 (Lifted + Performance Top)

Performance Testing

Onto the lab bench for full pressure vs. flow rate testing to take a complete look at performance in all possible conditions.  I’ll be doing my normal pump PQ testing which includes measurement of pressure differential across the pump from shut off flow rates to the maxium of my test rig.

  • Flow Rate – King Instruments 7520 with valve.
  • Pressure Differential – Dwyer 477-5 and custom 1/2″ ID T fittings to ensure flow is not disturbed entering or leaving the pumps.
  • Reservoir –  3″ ABS custom built with 5/8″ fittings for minimal restriction and nearly instant bleeding of air.
  • Power Supply and Current (Amps)  – Mastech HY3005D variable power supply
  • RPM –  Mastech MS8209 to read frequency in Hz.  Occasionally I have also used my Crystalfontz CFA-633, but find the Mastech is much more precise.  Most fan controllers only provide approximate RPM.
  • Warm Up/Bleeding – The pumps are typically allowed to warm up at least 15 minutes and all air is bled out of the loop prior to commencing.

Testing in progress


Voltage Requirements for “STRONG” performance

While 24V seems to do very little for the PMP-450 or vario pumps, having the ability to control voltage above 12V is critical on this pump to get full performance.  While 12V still provides a very good amount of power, it’s not enough to get full potential out of this pump.  I would simply suggest trying the pump at 12V and if you want the extra performance, then consider a means to feed the pump 24V.  The Koolance CTR-SPD24 is a great solution to converting the typical PC 12V to controllable 24V.

I’ll be showing you the relative performance differences at various voltage levels, starting at 12V.  You should also be aware that these pumps do not “Undervolt” very much.  11V is about the minimum voltage where the pump is willing to start, so those that are extremely particular with noise level or having the ability to turn the pump down will be better served by the PMP-450 or variable speed model.


Voltage Controller Connection

Test Results Detail

The pump scales with voltage very well.  12V would be plenty of power to exceed 1 GPM for average to low restriction systems and consumes a nice low 13 watts.  While 24V is sufficient to nearly get 1 GPM on the most restrictive 5 block+ type system, but it does consume a more hungry 30 to 36 watts.






WOW…over 8PSI at Shutoff, very impressing pumping power!   This is more than the PMP-400 series even after modifying with an aftermarket top.


RPM scaling of the PMP-450S and PMP-450

Comparison to the PMP-400 plus COV-RP400 top


Comparison to the PMP-450


While I haven’t tried the many flavors out there, I wouldn’t recommend them for this pump at high speeds. The higher speeds of this pump makes it susceptible to vibrations at very high speeds.  Stick with the factory top for anything over 12V.


I’ll be including this pump in my future noise comparisons, but subjectively I have a difficult time perceiving a difference between the PMP-450S running at 24V vs 12V or the PMP-450 at setting 5.  I am sure there is some sort of measurable difference (It is turning 1000 RPM faster), but it’s extremely small when the pump is decoupled properly and not likely to be noticed in your typical fan speed system.

When I stop and think about some of the other high-powered pumps I have tested in the past, such as the Iwaki RD-30 or Alphacool AP-15, this pump is subjectively superior.

Noise testing will be coming soon…My only suggestion is consider your own tolerance level with the PMP-450 vario pump.  If you’re happy with that pump at setting 5, you’ll likely be happy here as well.  However if you find setting 5 is too much and resort to setting 3, then you probably should stick with the variable PMP-450 model.   In other terms I would estimate the following:

  • PMP-450 = Setting 1,2,3,4,5
  • PMP-450S without controller = Setting 4.5
  • PMP-450S with voltage control = Setting 4,5,6,7,8


The PMP-450S is an excellent pump, and it does take the crown for most power between the PMP-400, PMP-450, and PMP-450S.  The trick is the requirement for a voltage controller feeding it more than the standard 12V.  Fortunately, Koolance has developed a controller to do just that if needed.  The pump in stock trim is compatible with 1/2″ tubing, so the pump has a very upgrade friendly path.  Here are some pros/cons:

  • King of Pump Power performance for under $100
  • Cool motor operation (metal pump housing keep motor running cool)
  • Factory 1/2″ Tubing compatibility
  • Factory stand allows pump decoupling without creating heat trap problems
  • Factory RPM wire
  • Metal housing minimizes PCB flooding risk if o-ring is improperly sealed
  • Factory top is larger in size than PMP-400
  • Not electrically or heat dump efficient as PMP-400 (A bit more heat added to the loop)
  • Requires a voltage controller and 24V to get full power performance
  • Higher speeds are more sensitive to the top used, suggest sticking with the factory top for high speeds.

So there we have it.  The PMP-400 (DDC series) are no longer king of power.  The Koolance PMP-450S with factory stock top when operated at 24V will produce more pumping power.  At 1.5 GPM this pump will produce around 6.7PSI, the PMP-450 @1.5GPM produces about 4.4PSI.  That translates to about a 50% increase in pressure over your typical PMP-450 at setting 5.  That’s about equal to running 1.5 PMP-450s in series.  That should translate to about a 25% improvement in flow rate for your average system vs. running a PMP-450 at setting 5.

For a more detailed flow rate estimation, you can try this pump in the latest pump/rad estimator here.

I’m personally a big fan of this along with the PMP-450 and PMP-400 pumps.  They all have their own pros/cons.  The PMP-450S is focused on raw 24V power.  At 24 volts it’s basically 1.5X as strong as a PMP-450 in the same package, it has the more desirable metal pump casing which keeps the pump running cool, and it’s less likely to have PCB water damage.  It may not be as efficient as the PMP-400 series pumps, but that’s generally of less concern once you get to triple rad sizes or more.

I could see people buying this pump to start out their system and simply running it at 12V until some time down the road when they expanded to a more restrictive system.  Then they could simply upgrade the pumping power by adding the 24V controller. At 24V, this pump is going to be more than enough power for even the most restrictive of setups such as full motherboard blocks etc.  You won’t need that for your typical CPU/GPU loop, but it’s nice knowing the power is ready to be tapped with a simple voltage boost.

Where to buy

There are only two places where I shop that carry the pump and controller, and I’ve included links to both below:

Direct from Koolance – PMP-450S CTR-SPD24

Sidewinder – PMP-450S CTR-SPD24


  1. […] good consistent test method. Special thanks to Tim from Koolance.com for sponsoring the PMP-450S. For the full detail review, you can find that on my site, but I'll skip over that and just give you my summary charts and conclusion here. You do need […]

  2. PepeLapiu says:

    Hi Martin,
    Can this pump run on it’s back?
    Meaning the inlet pointing up with water coming in from the top and the outlet beong horizontal.

    • Martinm210 says:

      Yes, while they prime and bleed faster with the outlet up, just about any orientation is possible. Some of the bay reservoirs even put the into an inverted position where the impeller inlet is pointing down and are successful with that. As long as you are careful about priming the pumps so they don’t run dry you can run any D5 or DDC variant in pretty much any orientation. I have run D5s myself with the outlet pointing down. It is a bit of a pain sometimes to clear out the air pocket initially, bit with some case rotation and patience to ensure it is primed made it work just fine. The magnet in the impeller holds it in place fairly well.

  3. David says:

    Great Site btw,

    So u don’t recommend a top for this pump but would u consider the Danger-Den Monsoon a top? i was looking to replace my D5 with this D5s but when u mentioned not to add a top if going over the 12v i now get a bit concerned.

    • Martinm210 says:

      I had some vibration issues testing with aftermarket tops on one sample. seemed as if the volute isn’t a perfect spiral like the OEM top it spins fast enough at >12v that the bearing can vibrate which could lead to early wear. I wouldn’t do it unless you kept the pump speed down.

  4. David says:

    OK Thanks. ATM my system is getting 1.75GpM (6.6Lpm) so was looking to push it over the 2GpM range. Guess ill take a look into the pmp500 when this 450 dies. but its only about a year old. Thanks for the fast reply back.

    • Martinm210 says:

      1.75 is pretty darn good. I generally don’t worry much unless I’m below 1.0. I suppose you could always try an S and adjust voltage as needed. D5s do seem to vary quite a bit in how well they are balanced. I have seen some that are very well balanced with zero vibration related issues and others that spiked in noise level at specific RPM levels. Same goes for the S models. Luck of the draw has a lot to do with it and you’ll know when you have vibration issues, the noise is pretty apparent. Also some tops are better designed than others so too many variables. I think the issue is a combination of impellers not being perfectly balanced and some aftermarket tops using a simple curve in the volute rather than a full spiral. The simple curve doesn’t balance forces on the impeller very well so too much lateral force plus imperfect impeller balance means vibration.

  5. Bj says:

    Going to run a 450s with this for a while at 12v until I complete my build, im tight for space in my case. This screws the pump in and should secure pretty tight so I shouldn’t have any vibration issues should I? Or should I have ordered the 450 vario and just stuck it on 5.

    Then when I finish my loop with more GPU and ram/mb blocks then I’ll increase the voltage to 18v.


  6. ca says:

    Hi Martin,
    Great review! Regarding the aftermarket top, did you happen to test the 450s with Koolance’s COV-RP450 rev. 2? This would be a great pump for my setup and with space being a concern, having a top and reservoir combined with the 450s would fit my needs best.

  7. […] I had the pump running at the 16.5V that Martin’s Liquid Lab specifies provides for maximum flow. I turned it down to 12.5V and that reduced the vibration significantly […]

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