The first sign of an expensive cooling decision may appear long after the system passes its acceptance tests, when a new server platform arrives and the existing infrastructure cannot accommodate it without substantial changes. Pumps still operate within their specified ranges, cold plates still transfer heat, and the cooling distribution unit still performs its intended function, yet the installation no longer fits the computing equipment that the site needs to support. What looked like a successful engineering decision during construction can therefore become a constraint during the next hardware transition. The difficulty rarely comes from heat transfer alone, because the surrounding hydraulic architecture determines how easily the installation can accommodate new requirements. A system designed around a narrowly defined operating point may deliver excellent performance under its original conditions while offering limited room for change.