Don't forget that Pis also draw quite some power while idle. The Pi 4 draws around 3.4 Watts [1], or around 2.7 Watts since they are running headless in a server setup you'd probably disable HDMI [2]. Times fourteen that's 37.8 Watts just sitting there. An idling headless Desktop PC will be below that for sure.

[1] https://magpi.raspberrypi.org/articles/raspberry-pi-specs-be...

[2] https://www.pidramble.com/wiki/benchmarks/power-consumption