AMD did not impress their fans by denying warranty if the performance "OC" bios switch was used on their Radeon HD 6990, but XFX have stepped up to the plate and are now saying that they will be fulfilling their warranty even if AMD won't.
XFX told Kitguru that they'd be offering it, with a statement saying:
XFX will warranty the 880Mhz OC Usage as per our usual RMA terms, as long as there is no Consumer Induced Damage etc, as per our usual terms and process for RMA's
XFX strongly believe that if you add a performance enhancing switch which allows the end user to ENHANCE THE CARDS PERFORMANCE, WE Believe it is only right to warranty this benefit,
Further to this, if you wish to guarantee total stability of overclocked product, XFX recommend that consumers use our performance range of XFX range of Power supplies, offering our true wattage guarantee, and easyrail technology, with the best pairing being 750w onwards both core and Modular editions.
This is great of XFX to do this and I would expect other AMD partners to step up and follow the same path - if AMD aren't showing love, then partners will only look better by doing so.