Thank you all for your comments. I ran Cinebench this morning and noted these additional temps.
Idle with front fans off: MB (motherboard): 41°C, PCH 72°C-74°C, VRM 46°C-47°C
Idle with front fans at 30%: MB 43°C, PCH 74°C, VRM 47°C
Idle with front fans at 100%: MB 36-40°C, PCH 67-74°C, VRM...