If your machines are all hypervisors you could migrate important VMs to a couple hosts and turn off the rest. You could also possibly throttle the vcpus, which

If your machines are all hypervisors you could migrate important VMs to a couple hosts and turn off the rest. You could also possibly throttle the vcpus, which would slow down the VMs but allow you to run the machines cooler, or more VMs per machine. Finally the ones with long running jobs could just be snapshotted and powered down and restored later, resuming their computation. There's a reason us old fogies were so excited when virtual machines got increasingly robust. We could use them to solve problems quickly that used to be nearly impossible.