Don't confuse age with ability. I have an old mustang what will destroy my 911 on the track (with some supercharger and suspension enhancements).

Grin mining for Cuckatoo31 or c31 on GPU's favors large frame buffers. It's been designed to run in 12 or 14 gb memory which is why the sapphire board trying to target. Otherwise you have deploy a memory paging or solver overflow routine which decreases fidelity (real life performance).

From what I've seen in the labs, the sapphire board outperforms the 1080ti mining C31 undermining pool conditions even though 1080ti reports 10% better performance.