Will a Sata II adapter work at SATA III speeds with a SATA III SSD?
I have an Intel 520 180G SATA III SSD that I am looking to use with a SATA II Icy Dock Adapter.
Will it cause a performance degrade to SATA II?
Everything always works at the slowest speed in the chain. In this instance, since you'll be connecting a SATA III SSD to a SATA II adapter, you'll be working at the SATA II transfer rates. You won't be getting all of the advantages a SATA III SSD has to offer, but it'll still be better than a mechanical drive.