Newer generations of DRAM (both GDDRx and the DDRx used in desktops and servers) are dense enough that they need on-die ECC. But that only offers some protection for data at rest, while the traditional kind of ECC involves also transmitting extra bits in order to also protect against transmission errors, providing end-to-end data protection. I don't think Nvidia has started allowing the latter kind of ECC to be enabled on consumer products.