Alphacool NexXxos ST30 280mm Radiator Review

Technical Specifications as listed by Alphacool:

The following Technical Drawing of the ST30 280 which is courtesy of Alphacool offers an overall length of 317.5mm

Dimensions Measured on the Radiator Tested:

The review sample measurements only differ by up to 0.5mm to the Technical Drawing sizes which is close enough for us.

The ST30 280 review sample measured in at 29.5mm thick and surely is the definition of a slim radiator. With it’s 140.x stables mates along side, the ST30’s thinness (rather than thickness) is much more obvious.

Radiator Core Dimensions:

The 16.5 mm thick core is made up of a single layer of 14 x 1.5mm copper tubes which are arranged in the standard U-Flow configuration. The fin arrangement consists of single serpentine fins which are louvered and has a 16 FPI count. This core figuration, on paper at least, appears to be tuned for low to medium speed fans. We’ll have to wait until our performance tests to find out if this turns out to be the case..

The following picture is a reference which shows a typical U-Flow coolant flow path, where the coolant travels up all the tubes on one side (left in pic) of the rad and then returns down the other side. U-Flow is most easily recognized when the port end has 2 separate tanks, such as those on the ST30 280.

The louvered fins were spaced quite evenly between the tubes on the review sample, despite the following photo showing a fin count spread of 15 – 20 FPI.

Finish and Features

The satin black paint finish on the ST30 280 is silky smooth and blemish free. This latest revision of Alphacool NexXxos radiators with the blue logos have a much better overall finish than previous versions.

A small Alphacool logo is present on each side. The painted blue logo represents the latest (4th, maybe 5th) generation of the NexXxos series radiators. When floor mounted and the logo will be the right way up, but will be upside down when roof mounted.

Screw protection plates are fitted under each fan attachment hole on the ST30 280.

In these two photos silver colored screws were used to better show the screws on the protection plates.

These protection plates will save the radiator from damage if custom length screws are used and are especially useful on the ST30 as the fan mounting holes are located directly above the tubes.

When using the supplied 30mm screws to attach a 25mm fan directly to the radiator, the screws just bottom out on the protect plate as the fan is firmly secured.

This is almost a perfect combination of screw length and plate depth. The 30mm length screws are the ideal length for direct attachment of a 25mm thick fan and for mounting the radiator with a fan onto a case panel.

Below a 35mm screw is fitted beside the 30mm. This 35mm screw ran out of thread just before touching the protection plate. Without a grill and or gaskets and the case panel (or mounting bracket) to go through, these 35mm screws are too long to use, hence our suggestion earlier that for a Push/Pull set-up you will likely need to purchase addition set of 30mm length screws.

We have expressed our concern previously about Alphacool’s decision to use a 16mm spacing between the central fan attachment holes. The industry “standard” is 15 mm, and why they have chosen to use 16mm is still unknown. I have seen build logs where users have had to unnecessarily modify their cases to accommodate the screw locations on the 140.x Alphacool radiators.

We just looked at the spacing between fans and while that 16mm is bothersome, of more concern is the spacing for each fan: in particular the spacing across the width of the radiator.
I am unsure if there is an industry standard for the distance apart fan mounting holes should be, but I am certain that all the 140mm fans I have are made with a 125mm spacing.

Below we see a ~124mm spacing at one end of the ST30 280. This is usable, but only just. Because the supplied screws have a thicker shank there is less wiggle room to adjust the fan’s position when starting off the threads. Therefore a tighter tolerance is needed in manufacturing for the threaded screw holes to match up with the mounting holes on a fan.

The spacing across the 2 center sets of holes was worse at ~122mm than at the ends.
Due to this poor spacing I was not able to get all 4 screws in for each fan when mounting them onto the ST30.

This is unacceptable and quality control missed the mark big time on this one.
The “tell tales” of scratched paint around the screw holes are not just there from me fumbling around. The holes are not positioned anywhere near close enough to allow for trouble free fan installation.

Having said that I did take some photos taken with fans attached, but only 3 screws per fan were able to be used.

In addition to the screw holes being incorrectly spaced, they are also not square to the radiator side panels as can seen on this first photo. (click to open full size in new tab)

Notice the the gap distance between the fans and then also use the top edge of the casing as a straight reference to give an indication of what I mean by the fan mounting holes not being square.

The ST30 280mm is fitted with just 2 G 1/4 ports.
No alternate ports are on the other side or ends of the tanks.
and no ancillary port is fitted to the return end.

This leaves us with one very “traditional” option for installing the inlet and outlet fittings, and no option of a fill/bleed ports, or drain taps and temp sensors with additional fittings being used.

The current NexXxos range including the ST30 280mm have the threads of the G 1/4 ports painted black.

It is unavoidable that paint will chip away or get scraped off when screwing fittings into the threads and where will these paint chips end up? The most likely answer is in the micro channels of your block, possibly reducing the flow rate and overall performance of the system.

Another issue which we encountered is that the inlet and outlet tanks of the ST30 are very short, or more specifically the the G 1/4 ports are positioned very close to the end of the core (as seen in the above photo).
This means that many fittings are not be able to be used when fans are attached on the port side of the radiator.

Above we see that the base of a Bitspower 3/8 x 5/8 compression fitting was not able to be screwed in when a fan was already installed. This is a very commonly used fitting with dimensions similar to many other fittings on the market. To not be able to fit a common medium sized fitting seems like an oversight in the design process.  There is no chance therefore of using any 3/4″ OD fittings.

In the following photo we see one of Alphacool’s own HD series hard tube fitting has no chance of screwing down. The base fits, but the collar hangs up on the fan frame.

Here is the same fitting with the fan removed to show the the overhang of the collar. With fans installed on the other side this just works. The collar tightens down pretty firm (with a tube installed) just before it bottoms out on the frame.

I found that the maximum width a fitting can be with fans attached on the port side is 19.25mm

Internal Cleanliness:

On a more positive note, the latest revision of NexXxos radiators (with blue logos) are coming out with a different cleaning process after manufacturing. This new process has resulted in unexpected and surprisingly clean internals. I recently flushed/cleaned 5 different current version Alphacool radiators including the ST 280 reviewed here, and all were within reasonable expectations of being clean and free of excess amount of debris after the first rinse.

We still strongly advise cleaning all new radiators prior to use, but it is great to see that what was a terrible problem has now been rectified.

So here we have a slim ~30mm thick radiator with a low to medium density core. It has just 2 ports which unfortunately have been installed so close to the core that many fittings can not be used when fans are installed on the port side. Screw protection plates are fitted but the screw attachment holes are out of alignment so only 3 of the 4 screws for each fan could be fitted. The paint finish on the sample was excellent but we feel that the paint on the inside of the ports could lead to unwanted problems.

Let’s see how it performs…