Pump Performance

The Bitspower D5 Vario is a Xylem D5 in a Bitspower dress, which means it already has a history of reliable and good performance backing it. But as with every product we receive, it underwent full testing, including for the pump itself. We usually first test the RPM response as a function of the control mechanism, but with the D5 Vario, it is just a dial knob on the back with positions 1–5, and there is no RPM reporting, either. So seen above is the rated RPM for each of these positions, and typically, you would switch between positions 3–5 depending on whether you want to prioritize noise or performance. This is why the D5 PWM motor is getting more and more popular with time.

To test the D5 pump by itself, I used a reference D5 top from XSPC (XSPC D5 Bay Res) with the Bitspower D5. This is to help decouple pump and pump top performance, which will be tested separately below. I used this D5 combination in a simple loop of reservoir-in to reservoir-out with pump power from an EVGA SuperNova 1300G2 PSU, as well as a Dwyer 490-1 wet-wet manometer to measure pump head in PSI and a King rotameter to measure average flow rate in gallons per minute (GPM). This P-Q curve for a pump provides extremely useful information as it dictates the average flow rate in a loop when any flow restriction is added through such components as blocks and radiators, under others. To produce an ideal and yet realistic data set, the P-Q curves below are thus for the pumps in a closed loop with minimal flow restriction.


I have included some other pumps that have been developed within the few last years for comparison. A lot of the more budget-oriented pumps introduced lately aim to match the Xylem D5 Vario on position 3. As such, I have included that setting as well, in addition to position 5 (full power). The Alphacool VPP755 is a newer "D5-replacement" pump sold by Alphacool, with a different design but in a similar housing as the Xylem D5, and it ends up outperforming the D5 Vario (w/XSPC top) ever so slightly. The rest of the lot, except for the Xylem DDC, of course, hover around the lower end with only the XSPC X2O 420 in the XSPC Ion and the Topsflo TDC doing better.