I assembled the same loop as before except with a Dwyer 490-1 wet-wet manometer with the high pressure and low pressure ports between the inlet and outlet of the pump to measured the pressure drop across it (the loop had a valve to help increase/decrease liquid flow restriction easily) and a King Instruments rotameter helped measure the average flow rate. The pump was fed 12 VDC constantly here. In order to provide context, I did the same with a few other pumps- the EK SPC-60, the Topsflow TDC, the XSPC X2O 420 and of course the Laing D5 Vario pump on the same XSPC bay reservoir once the VPP755 was done with testing. I set the D5 style pumps on Position 5 and 3, with the rest at full speed considering they are relatively weaker pumps and really only comparable to the D5 at Position/Setting 3.
Well, well, well. I am not sure how Alphacool measured the max flow rate it specified but I am certainly glad that is not the case. This is a real powerful pump, and stronger than the Laing D5 in almost every which way. Please note that the exact top used will also impact the absolute numbers, which is why I used the same top for the Laing D5 as well as the VPP755 here. The better performance is all the more impressive knowing that the Laing D5 is running at a higher speed too, at least based on the RPM readouts. At Position 3, both were too close to distinguish easily but I would still give the overall edge to the VPP755 here. The Topsflo TDC aside, the VPP755 (and the D5) on Position 3 perform nearly the same and it will come down to the specific liquid flow restriction in your loop to distinguish between them.
What about pump noise? Alphacool was claiming better performance (and they did achieve that) but also much lower noise levels. So I used the Eispumpe VPP755 and the D5 Vario on the same XSPC top and the same reservoir-pump only loop, and placed it in an anechoic chamber of size 5′ x 8′ with ambient noise level ~19 dBA. The PSU was outside with a double seal around the cable outlet so noise measurements were from the pump only. A sound probe held 6″ away was used to measure the sound volume in dBA after air was bled from the loop as much as possible.
I am getting more, and more impressed here. I was expecting noise to be lower over considering that the pump speed was less on the VPP755 at the same knob position as the D5 Vario but the increased performance led me to believe it might even out. Turns out there is a significant decrease in pump noise here even with both pumps at the same speed- especially at higher pump speeds. At lower pump speeds/knob positions, the difference is not much but given many operate the D5 Vario at Position 3 or 4 because it is too loud for them on Position 5, the VPP755 may be exactly what they are looking for. In fact, the VPP755 on Position 5 is quieter than the D5 on Position 4 and this is no mere feat.
We now have data that shows the VPP755 is not just a better performer but also quieter than the D5. What about practical situations? Will these differences come into play much here or will it be within error margins? To find out, I assembled the same loop I did for testing my other pumps: An XSPC Raystorm Pro CPU block, a Swiftech Komodo R9-LE GPU block, a Black Ice Nemesis GTS 360 radiator and 2 sets of Koolance QD3 quick disconnects to go with 6 Bitspower 1/2″ x 3/4″ fittings and Primochill Advanced LRT tubing in the same size. The blocks are one of the least restrictive in each category and the addition of the QDCs and relatively more restrictive radiator brings up the average restriction close to what most loops would have. Aside from the pumps used in the P-Q testing above, I also added in an 18 W Laing DDC PWM (At 100, and 50% PWM signal) and a Swiftech MCP30 (a slower version of the MCP50X, again at 100 and 50% PWM signal and using the MCP50X top). Note that the DDC does not have a big difference in RPM response from 50% PWM to 100% PWM, and as such the respective numbers will be similar.
I would also have a plot of pump noise at a normalized flow rate, and normalize everything to the flow rate of the XSPC X2O 420 which has no pump speed control. However, given the discrete pump speed control here, the VPP755 and the X2O 420 did not match up and so I hope the chart above will suffice. It is certainly helpful in painting a picture that continues to make the VPP755 an impressive product. There is no pump that offers a better flow/noise ratio than the VPP755 I have tested so far, and there is also performance to satisfy most if not all users too from the same product. To be honest, unless you have an extremely restrictive loop or can’t fit the VPP755 in, I can’t think of any reason to go with the Laing DDC or the Swiftech MCP50X anymore.
Before we wrap up, I would like to bring up two more factors that can influence your decision: Power consumption, and longevity. The former I did not test owing to the pump getting its power directly from the PSU and fan headers not being a concern as far as power draw limitations go. If you are interested, Extreme Rigs has detailed coverage on this here. Longevity is again hard to test here considering the sample size is 1, and I can’t afford to have a loop run by itself for months for every single pump I have here. So I generally do an acute intense test with each pump powered and running at full speed for at least 200 hours (including test time). The VPP755 is still running fine, so take that for what you will. I realize this is not a true indicator of reliability, as 1 of my Swiftech MCP50X pumps is now beyond use and that was not caught during review time. As always with new pumps, it comes down to product warranty (there is a general 2 year warranty here) and customer support.