Performance Testing- Part 1

I have tested the SPC-60 pump in more detail before, which definitely helps. I will also reuse a lot of that information here since this pump tested well within any error margins of the other standalone pump from an older review.

To begin with, I want to chart pump speed and noise levels as a function of the supplied PWM signal (%). I have the EK-XRES 140 SPC PWM Classic RGB in a simple reservoir-pump-reservoir loop with the pump connected to an Aquacomputer Aquaero 6 XT controller to provide power and monitor RPM. Noise is measured in an 5" x 8" anechoic chamber with an ambient noise level of ~19 dBA based on a sound probe held 6" away after air is bled from the loop by as much as possible.


Surprisingly, EK did not mention any pump speed ratings to go along with the rated PWM duty cycle of 20%–100%. But then you take a look at the images on the product page for the EK-XTOP SPC-60 and see a full RPM response curve. This particular sample hit 2556 RPM at 100% PWM and went all the way down to 816 RPM at 20%, with a further dip to 511 RPM at 16%, which is lower than I expected. As such, the pump does hit the advertised 20%–100% PWM duty cycle, and the RPM response curve is mostly linear in this region until lower RPM where it dips more like a voltage-controlled device. The pump is also reasonably quiet, which is something people would like to have in a small duty pump.

The pump also had a maximum operating current draw of 0.46 A (5.5 W on the 12 VDC rail), which is quite close to the rated 6 W power draw. The pump is definitely low-power relative to the more popular D5 and fully fledged DDC. That and PWM control being more efficient than voltage control in general means there is no need for a heatsink, and a standard 1 A 4-pin PWM header is plenty to power it as well.

To get a better idea of how the pump performs, I assembled the same loop as before, but 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 measure 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. In order to provide context, I did the same with the Topsflo TDC, a XSPC X2O 420 pump, which also comes as part of a reservoir/pump combo, and a Laing D5 Vario pump on an XSPC bay reservoir. I set the D5 to Setting 5 and 3 (you will soon see why), and the X2O 420 only takes 12 VDC directly from the PSU for a total of 5 P-Q curves, including the Topsflo TDC, which was also set at 12 V.


Generally speaking, you would like to see a pump have a good balance of pressure head and flow rate. The higher both are, the better, of course. The Laing D5 has great maximum flow rate, but at the expense of slightly lower head compared to the Laing DDC. As such, the D5 is recommended for a lot of low-medium restriction loops and, being quieter and cooler than the DDC along with having proven reliable over the long term, is one of the most popular pumps in this industry. This is also why it is my standard pump for comparison in all pump tests.

The SPC-60 pump in the EK-XRES 140 SPC PWM Classic RGB—along with the Topsflo TDC and X20 420 from XSPC—is in a similar position in that while it has lower maximum head and flow rate than the D5 on Setting 5 (4800 RPM here), it can be compared to the D5 Vario at Setting 3 (~3500 RPM here). An average loop with a CPU block, a GPU block, some fittings, and a radiator will have enough restriction to where these three pumps will perform similar to a D5 Vario on Setting 3. But overall, the EK SPC-60 pump has the lowest maximum head pressure and flow rate of the pumps tested thus far and is on par with the XSPC X2O 420 at the point of inflection.