Alphacool ST30 X-Flow 360mm Radiator Review

The Data

As all our testing for 360mm radiators are performed with the exact same equipment, using the exact same methods we have decided to (try and) keep each radiator’s pages uncluttered by posting our testing methodology, test set-ups and equipment used in a single location. To see exactly how the tests were carried out, details of the test set ups and equipment used, please check out the RRU Test Setup page.

Restriction Test

It is generally agreed that radiators are one of, if not the least restrictive components in the water cooling loop. There are some exceptions however, so this must still be verified through testing:
The above photo is for referencing the restriction test bench. The ST30 X-Flow is not loaded so please disregard the data in the picture as it does not relate to the its test results.

Here is the raw data at the tested flow rates, displaying the measured Differential Pressure across the radiator as flow rate was increased.
The table numbers indicate that the ST30 X-Flow is a very low restriction radiator. In fact our differential pressure manometer was unable to detect a difference at the lowest flow rate on the flow meter. Numbers in isolation sometimes only tell half the story. By plotting against other components it more easily shows the whole story.

We use a HeatKiller 3.0 CPU block as the reference in this next plot for two reasons. Firstly there is little chance of the plot being cluttered by curves overlapping and secondly it gives a reference point against a fairly common loop component of average restriction.

As with all previous radiator restriction plots, we have limited the maximum flow rate displayed to 2.0 GPM as we suspect there are very few systems that operate above 2.0 GPM. For more information on how to read a restriction plot check out our guide.
This plots indicates the ST30 X-Flow is a very low restriction loop component when compared to a CPU block of average restriction, but what about other radiators?

The next three plots show the restriction level at three different flow rates compared to the other Slim 360mm radiator that have been tested. We consider the chosen GPM rates to represent systems which have low, medium and high flow rates. Additionally, a plot has been included which shows the comparison against all the radiators that have been on our restriction test bench.

As it turns out the ST30 X-Flow and the regular ST30 360mm models share the exact same core with only slight differences for manufacturing tolerances. Therefore with the same amount of tubes which are the same thickness we expect to see the X-Flow pressure readings to be “almost” exactly half of the standard ST30.

We expected the ST30 X-Flow to record low restriction reading because it is a X-Flow radiator and that is exactly what we found. At all 3 flow rates plotted, it has the lowest restriction level of all the slim 360 radiators.

We know the the Nemesis GTS X-Flow has a more restrictive flow path than the ST30 X-Flow because it has more tubes which are also thinner, but we thought it interesting to isolate the 2 models and plot them against each other.

Finally for restriction let’s take a look at where the ST30 X-Flow 360mm fits in relation to all the radiators we have tested. For this plot, only results for 1.0 GPM have been used for the comparison.

When put into context with all the radiators at 1.0 GPM, the ST30 X-Flow fits our criteria for a low restriction radiator. This means pump power is not high on the list of considerations, even if you’re intending to run several of them in your loop.

Onwards to Thermal Performance!