Sniper is a next generation parallel, high-speed and accurate x86 simulator. This multi-core simulator is based on the interval core model and the Graphite simulation infrastructure, allowing for fast and accurate simulation and for trading off simulation speed for accuracy to allow a range of flexible simulation options when exploring different homogeneous and heterogeneous multi-core architectures. The Sniper simulator allows one to perform timing simulations for both multi-programmed workloads and multi-threaded, shared-memory applications running on 10s to 100+ cores, at a high speed when compared to existing simulators. The main feature of the simulator is its core model which is based on interval simulation, a fast mechanistic core model. Interval simulation raises the level of abstraction in architectural simulation which allows for faster simulator development and evaluation times; it does so by ?jumping? between miss events, called intervals. Sniper has been validated against multi-socket Intel Core2 and Nehalem systems and provides average performance prediction errors within 25% at a simulation speed of up to several MIPS. This simulator, and the interval core model, is useful for uncore and system-level studies that require more detail than the typical one-IPC models, but for which cycle-accurate simulators are too slow to allow workloads of meaningful sizes to be simulated. As an added benefit, the interval core model allows the generation of CPI stacks, which show the number of cycles lost due to different characteristics of the system, like the cache hierarchy or branch predictor, and lead to a better understanding of each component?s effect on total system performance. This extends the use for Sniper to application characterization and hardware/software co-design. The Sniper simulator is available for download at http://snipersim.org and can be used freely for academic research.