I believe there are quality issues with XSPC RX series and Feser TFC series radiators at the moment. The RX series are having nightmares - first, they packed them with the paint still wet, then there were holes missing, shell sides not lining up, threads drilled in the wrong place, big lumps of flux blocking the cores. The reports just went on and on. A couple of places just aren't stocking them and one place I know is testing every unit for fit and flow rate, then touching them up with black gloss paint before they ship them out.
I believe Feser's QC is significantly better so those ones are probably just not leaving the factory.
I don't know what's happened it that particular factory, but I would stay well away from Feser or XSPC radiators until you start to see good reports about them again.
You know that some craftsperson (don't want to be sexist here, but it's probably a bloke) in Yorkshire is hand building every Thermochill, then testing it before despatch, so you know they're good. And with the current exchange rates, they are also CHEAPER as well as better.