An apparatus and method utilizes system memory as backing stores so that local graphics memory may be oversubscribed. Surfaces may be paged in and out of system memory based on the amount of usage of the surfaces. The apparatus and method also prioritizes surfaces among different tiers of local memory (e.g. frame buffer), non-local memory (e.g. page locked system memory), and system memory backing stores (e.g. pageable system memory) locations based on predefined criteria and runtime statistics relating to the surfaces. As such, local memory may be, for example, expanded without extra memory costs such as adding a frame buffer memory to allow graphics applications to effectively use more memory and run faster.