I was given the choice, to run memtest tonight and let it run all the way through or to try with random sticks of RAM tomorrow. I opted for the latter because it means not keeping the machine on all night long. But is it really more green? Those sticks of RAM have a certain environmental load too. Is it better to run energy using tests on the currently existing hardware or check every point of failure with a backup known working set? Which is more green? Should we even worry about such decisions at all?