This paper introduces SIMinG-1k-a manycore simulator infrastructure. SIMinG-1k is a graphics processing unit accelerated, parallel simulator for design-space exploration of large-scale manycore systems. It features an optimal trade-off between modeling accuracy and simulation speed. Its main objectives are high performance, flexibility, and ability to simulate thousands of cores. SIMinG-1k can model different architectures (currently, we support ARM (Available from: http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0100i/index.html) and Intel x86) using two-step approac where architecture specific front end is decoupled from a fast and parallel manycore virtual machine running on graphical processing unit platform. We evaluate the simulator for target architecture with up to 4096 cores. Our results demonstrate very high scalability and almost linear speedup with simulation of increasing number of cores.