End user computing generates 1% of global greenhouse gas emissions caused by production processes and subsequent electricity consumption during use. The concept of displacement has the potential to reduce this environmental impact by repurposing computers at the end of their perceived useful lifespan to extend longevity. Doing so removes the immediate requirement for new devices to be manufactured, therefore potentially slowing global demand and reducing embodied emissions proportionately. However, existing research implies that a combination of improving energy consumption efficiency experienced by new devices, plus ongoing inefficiency associated with aging devices, may be sufficient to counter the abatement gains achieved by displacement. Such energy efficiency gains are due to both continuing hardware and software innovation. As an example, recent research substantiates that alternative operating systems, such as Google Chrome OS, reduce electricity consumption when compared to other popular operating systems. As such, it is reasonable to suggest that repurposing legacy Microsoft Windows computing devices with a version of Chrome OS software will counter the new device efficiency theory and deliver abatement via the process of displacement. Consequently, the objective of this research is to test this hypothesis by quantifying greenhouse gas abatement values delivered by alternative computer operating system displacement strategies and compare the result to the impact of new device manufacture and use. This is achieved via a field experiment measuring the electricity consumption of two legacy notebooks operated in the workplace before and after repurposing occurs. To enable comparison with a new device strategy, two contemporary notebooks are also measured and the embodied carbon footprint contribution recorded. When compared, the results determine two key outcomes. Firstly, a 19% average electricity consumption reduction is experienced further to repurposing the legacy Windows devices with Chrome OS Flex, enabling the notebooks to exhibit energy efficiency equivalent to new devices. Secondly, the earliest point at which the legacy ongoing electricity consumption emissions and combined new device manufacturing emissions plus use phase emissions intersect, is during the 91st year of new ownership. Consequently, as almost a century must pass to compensate for manufacturing emissions, then displacement utilising alternative operating systems should be prioritised, where feasible, if global end user computing emissions are to be meaningfully addressed.