# How to do REMD using One machine?

**URL:** <https://gromacs.bioexcel.eu/t/how-to-do-remd-using-one-machine/1359>\
**Category:** User discussions\
**Created:** [December 30, 2020, 5:15pm UTC](https://gromacs.bioexcel.eu/t/how-to-do-remd-using-one-machine/1359 "2020-12-30T17:15:16Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![sam](https://avatars.discourse-cdn.com/v4/letter/s/5f9b8f/32.png) [@sam](https://gromacs.bioexcel.eu/u/sam)\
**Post date:** [December 30, 2020, 5:15pm UTC](https://gromacs.bioexcel.eu/t/how-to-do-remd-using-one-machine/1359/1 "2020-12-30T17:15:16Z")

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GROMACS version:2020.4  
I need to do a simulation (REMD) for 36 replicas on one laptop that has a processor i7 with RTX 2060 (6 cores). is this suitable for simulation in parallel?

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**Author:** ![jalemkul](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/jalemkul/32/18_2.png) [@jalemkul](https://gromacs.bioexcel.eu/u/jalemkul)\
**Post date:** [January 1, 2021, 1:12am UTC](https://gromacs.bioexcel.eu/t/how-to-do-remd-using-one-machine/1359/2 "2021-01-01T01:12:29Z")

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That will be wildly inefficient. You need at least one core per replica, otherwise your simulations will all just be choking each other for CPU time. And one core per replica is really the absolute lower limit, as any but the smallest simulation systems will still perform very poorly.