How can I identify individual GPUs in a multi GPU setup?

[Thunderdolt]

My system is stable and consistent. That means it's time to overclock. Here's the problem I'm running into: I want to do per-card overclocking, but every time I boot the machine, the GPUs are in a different order in Afterburner and GPU-Z.

Is there a way to either get the GPUs to always show in the same order or at least be able to identify them after booting?