So all the fans are intake except for the rad fan?
Front should be intake. Top should be exhaust. Rear should be exhaust.
Is windows even loaded? Or is this temps in bios?
68 is too high for a true idle. Since you just built this pc, is it still dealing with windows updates? It'll do that during what you consider idle and can sometimes take 3 or more days to finish.
Idle temps in a decent airflow will generally be 6-12°C above your room ambient temps. I've seen 50°C idles before, but at almost 70°C, either your airflow is seriously compromised and you've turned the pc into an oven, or the cooler isn't connected right (fan should be on cpu_fan header, pump on anything else) because at 68°C that fan should be at almost max speed and you'd know that easily or windows is under a load and you aren't at actual idle.