Major Update:
New sub-tiers have been created in Tier 2, namely Class A and B.
The major reason for the sub tiers is to differentiate between mainstream performance oriented boards, that is, boards with SLI ability and good OCing ability at a 'sweet' price point, from boards which have been in Tier 2 simply because they're SLI capable.
Class B boards aren't any bad, but they're more pressed to bring the SLI ability at an affordable price point than to combine SLI with a very good OCing platform. Class A boards are good for serious OCing as well as x8/x8.
New sub-tiers have been created in Tier 2, namely Class A and B.
The major reason for the sub tiers is to differentiate between mainstream performance oriented boards, that is, boards with SLI ability and good OCing ability at a 'sweet' price point, from boards which have been in Tier 2 simply because they're SLI capable.
Class B boards aren't any bad, but they're more pressed to bring the SLI ability at an affordable price point than to combine SLI with a very good OCing platform. Class A boards are good for serious OCing as well as x8/x8.