Danger Den DD12V-D4 Water Cooling Pump Review


Testing and conclusion

For my initial testing of the D4, I attempted to simply attach the tubing to the inlet and outlet on the pump, plug in the Molex power connector and start it up. I quickly discovered that this was not a great idea due to the D4’s light weight and small footprint.

With most other pumps I have tested, I could get by with just setting the pump in the bottom of the case and then using the weight of the pump to hold it in place. This is definitely not a good approach for the D4 as it is not nearly as heavy as full-sized AC powered pumps and it would not stay in one place. After taking the initial pictures, I promptly used the base plate as a drilling template and drilled out 2 holes large enough to secure the pump with #8 machine screws.

Once everything was nice and secure, I proceeded to get any air out of the pump by turning it on and off at 5 minute intervals and lightly tapping the sides of the pump to dislodge any air bubbles that were trapped inside the pump. The pump was a bit loud at first but that was apparently the result of air trapped in the pump as it quieted down nicely after I worked the air out of it.

Other than having to bolt it to the case, the installation process was very easy. The inlet and outlet fittings on the pump are ideal for 1/2″ ID tubing as it is not difficult to get the tubing onto the fittings but rim on the fittings provides a solid seal between the tubing and the pump and there were no leakage problems whatsoever.

The Danger Den D4

Click here for a larger image
Yes…I overdid the UV dye again…

During the testing of the pump, I was a little surprised by how well it moved coolant through the loop. The RBX with a #4 nozzle has quite a bit of restriction but the pump happily hammered the coolant through the loop. In order to check the flow a little more closely, I switched from a T-line setup to a loop with a reservoir as I did not have an inline flow meter on hand.

The results with the D4 with a reservoir in the cooling loop were also very good but it is definitely a good idea to use a reservoir with an internal divider plate with this pump or the rate and pressure of the flow from the D4 will turn the reservoir into a swirling bubble and foam generator.

For testing, I wish I would have had another pump in the same class but the only other model in the shop was an original version of the Rainbow Lifeguard Quiet One which is an AC-powered mega-pump. While I briefly considered running them side-by-side, I realized there would be nothing worthwhile from such a test as it would be comparing apples to oranges and the original RLQO is not even available anymore as Pentair Aquatics changed the design shortly after they bought out Rainbow. As such, I ran temperature testing with just the D4 and the other previously mentioned components.

For temperature testing., temperature readings were taken with an Omega 5830 bench thermometer using 700 series thermistors. To obtain idle temperature readings, I stressed the system with Toast for about 30 minutes and then let it set for another 15 minutes before taking the idle reading.

For load temperatures, I cranked up Toast for 2 hours and then recorded the readings from the Omega thermometer. With an ambient temperature of 20 degrees Celsius, the CPU temperatures were 27 degrees Celsius at idle and a very respectable 31 degrees Celsius under load according to the Omega unit. The D4 clearly moves enough water through the loop for the rest of the components to do there job.

Other notes and observations — the D4 ran exceptionally cool during all of the testing. I checked the pump housing several times throughout testing and it was never more than just slightly warm to the touch. As far as noise is concerned, the D4 does make a bit of a humming noise but it is much quieter than most watercooling pumps I have used and the humming could not be detected over the sound of the video card’s cooling fan.

Overall, the Danger Den D4 is an exceptional pump for watercooling systems. It is extremely small and yet powerful. As it is powered by 12v through a standard Molex connector, the pump turns on and off with the rest of the computer and it can be connected to a rheobus to tune its performance provided the rheobus is rated to handle 18w.

The only minor complaint I have is that it does not include mounting screws for attachment to the case but that is easy enough to remedy with a dollar or two and a trip to the hardware store if you do not already have the screws on hand. While some have complained that it is more expensive than some other pumps on the market, it is a good deal less expensive than many pumps I have bought for cooling loops in the past and it is a very well made pump.

Danger Den has yet another solid product with the D4 and I give it a solid 9.5/10 and the OCmodshop Seal of Approval. I would like to thank Directron for making this review possible. As always, they were great to deal with and they are a top notch source for computer gear.

  • Extremely compact
  • Leak-free fittings
  • Reasonable price
  • Solid flow and pressure
  • 12v powered with a standard Molex connector


  • Mounting screws are not included.