Value Two PC’s

My fiancé and I had two Alienware R13 Desktops. We recently upgraded and I’m looking to sell them, but I’ve never sold a “nicer” computer. Any helps in valuing them, what to look out for, and suggestions where would be appreciated. Additionally, I don’t know the most about PC’s so apologies if I’m missing any important details.

Mine:
I9-12900F
3080
2x16 DDR5
Liquid cooling

Fiancé:
I9-12900F
3060
2x8 DDR5
Air Cooled