GEM5 – “The gem5 simulator is a modular platform for computer system architecture research, encompassing system-level architecture as well as processor microarchitecture.” -http://gem5.org/

MARSSx86 – “MARSSx86 (MARSS for short) is a tool for cycle accurate full system simulation of the x86-64 architecture, specifically multicore implementations. Our goal is to create a simple yet efficient full system architectural simulation environment based on existing tools.” -http://marss86.org/

PTLsim – “PTLsim is a cycle accurate x86 microprocessor simulator and virtual machine for the x86 and x86-64 instruction sets. PTLsim models a modern superscalar out of order x86-64 compatible processor core at a configurable level of detail ranging from full-speed native execution on the host CPU all the way down to RTL level models of all key pipeline structures” -http://www.ptlsim.org

McPAT – “McPAT (Multicore Power, Area, and Timing) is an integrated power, area, and timing modeling framework for multithreaded, multicore, and manycore architectures.” -http://www.hpl.hp.com/research/mcpat/