35W is the way to go

35W TDP is the way to go for any fanless build, especially the very first one. Do not underestimate these CPUs, we're talking desktop-grade processing power here. At 12400+ CPU Mark, the i7-8700T is workstation material in our book. Here's our Coffee Lake selection :

Celeron G4900T 2C / 2T @ 2.90 GHz

Pentium G5500T 2C / 4T @ 3.20 GHz

i3-8100T 4C / 4T @ 3.10 GHz

i5-8500T 6C / 6T up to 3.50 GHz

i7-8700T 6C / 12T up to 4.00 GHz