If my server has only the cipher suites enabled which are defined by TLSv1.2 does that force a client to also use TLSv1.2 or else not be able to connect or can the connection fallback to TLSv1.1 or 1.0 and still negotiate the TLSv1.2 cipher? I do understand that the GCM block modes are TLSv1.2 only but unsure about the others.
It forces clients who report that they support TLSv1.2 to use it, and causes all other client connections, those who only support a maxium of TLSv1.0 or TLSv1.1, to fail.
At this point, unless you know exactly who your clients are and that they do, in fact, support TLSv1.2, (if this is in any enterprise Intranet environment, for instance) I would not recommend this configuration. There is a large portion of the Internet that does not yet have the level of support required for this to not turn out to be a disaster.