Too much lead, apparently, and people using brass when they should use copper.
If you drill through you get to Igor Lab's original articles here and here.
New AIO radiator testing reveals lead and other substandard materials — Caseking halts Barrow Dabel product sales in response
Igor's Lab found "huge amounts of lead" in one of the coolers.
www.tomshardware.com
If you drill through you get to Igor Lab's original articles here and here.