[churchx]

PC liquid cooling hardware is not very well fit for automotive purposes. Or even if it will work, it will work less efficient vs purpose optimized.
PC looks-based builds aside, one of main priorities for LC is quieter cooling. Quieter cooling with quieter/slower/less powerful fans needs rads of less FPI (and higher size/mostly frontal area, but also thickness), which will mean that they will be oversized (harder to find mounting space) and will weight excess (also because most common rads/cooling blocks for PCs are from copper or brass, vs automotive rads usually being aluminum) vs high fins per inch automotive rad optimized for powerful fans (noise matters way less under bonnet behind firewall and near relatively loud engine), that can net same cooling even if being of 4x times smaller frontal area (thus also less weight and easier to find space where to mount in cramped underbonnet space of modern cars).
Also even though common pumps used in PC LC scene (eg. Laing D5 or DDC series) are also 12V pumps, not sure they will respond well with possible voltage spikes in power and IIRC they also were certified upto 60C, not temps one may see under bonnet near hot engine. But if one will use just PC LC waterblocks/rads, but pump with automotive pumps, they are not designed for possibly higher pressure of positive displacement pumps vs lower pressure of PC LC centrifugal pumps (for which pressure matters too, but only as extra to quiet operation).
In short, not sure it's good idea.