Question about Thermaltake Pacific PR22-D5 Plus expansion tank and pump

I don't have the exact answer to your question and of course it depends on your components, because different cpus and gpus will heat up differently. I can tell you what my thinking would be. I would use two separate loops with two pumps and two radiators and give more radiator area to the component that can be overclocked better. If your cpu performs poorly in reviews then i wouldn't waste additional cooling power there either. Conversely, if your cpu is a top overclocker then i would put more cooling power there. If both components are equally overclockable i would give more radiator area to the component that gives you more fps with oc as a result. Look at oc reviews of your gpu and cpu and see how well they overclock and what the fps gain is. I would cool the component that performs better. That's how I would proceed. If you don't want an oc then I would only take visual considerations into account. What looks better and is easier to build would then be decisive for me. With Wakue, 1 x 120 rad area per component is enough to deliver enough cooling power.

A 360 rad is fine for two components. Some recommend 1 x 120mm fan area per component, others recommend 2. Since in your loop one pump, one impeller and two components are connected to each other, the temperature of the water will be uniform. Under load, both components will heat the water. There are people who attach importance to the order of the components. Youtubers have also tested wakus systems without a fan on the bike and the difference in temperature was surprisingly small. You won't notice any big differences in your system, no matter how perfectly you assemble it. My tip is to build something that looks cool.

Two loops also means two pumps, because you need one pump for each separate loop. This pump has one input and one output. You probably mean cooling two components via one, two, or more radiators. The d5 is the standard pump in most systems and will easily handle two components. I have a big tower and use it to cool the graphics card and cpu via a 240 and 360 rad.