I'd check to see if the server PSUs can be voltage switched
Look for a slide switch near the power cord connector on the power supply. Usually marked "120-240", and is usually colored red. This switch is designed to require a screwdriver or similar tool to change, and not be easily changed by an unaided hand. It may be hidden behind some plastic trim on some computers or servers.
If the supply isn't the usual PC power supply, and you can take the cover off the server, the power supply might have a jumper wire to choose 120V or 240V operation.
The above switch or jumper just configures the supply from a voltage doubler to a bridge rectifier. This is to get around 300VDC that is then fed to a high frequency chopper, then high frequency transformer, and then rectifier circuits to get the 5VDC.
Switching power supplies don't care if it's 60Hz or 50Hz. And the server won't care either.