A lot of servers I've seen have had 'chassis intrusion detection', which is a fancy way of saying they had a microswitch hooked up to one of the SMBus lines tha

A lot of servers I've seen have had 'chassis intrusion detection', which is a fancy way of saying they had a microswitch hooked up to one of the SMBus lines that could detect when the case is opened. Take one of those, and a Google-style Lead-Acid internal UPS, and you'd have an incredibly hard time getting access to keys held solely in memory. For the extra paranoid, accelerometers or a simple mercury vibration/tilt switch would make it even harder, at the risk of losing/hanging your server every time someone worked on the rack, or drove a heavy pallet cart nearby. I recall seeing somewhere a device designed for law enforcement, which was essentially a cart-style UPS with probes designed to be clamped onto, and penetrate, the power cable, allowing seizures without any power-loss, which I assume is for this eventuality.