Does sound strange.
I'm no expert on the Boxster cluster wiring, but you might consider these ideas: Is the cluster out of the dash while you are testing it? Is only one bulb of the three blowing? If so, you might want to try 2 things:
1) if you have a voltmeter, check the voltage at the lamp sockets. Be careful not to short anything (just being paranoid, but you don't want to risk your $1200 cluster by shorting something else on the board). From the look of ToolPants' image of the bulb holder, there should be some easy to access surface pads on the board where the holder makes contact. They should all 3 likely read the same voltage. If not, we may need to follow up from there...
2) Sometimes car electricals have issues with "floating ground" - if the cluster is not installed in the normal position (actually, even if it is...), make sure that any ground wire or connection is properly made. This may be a screw connection to a metal part or a jumper wire if it is not integrated into the wire harness. Floating grounds can cause current to run through an alternate path to ground that is not designed to handle the load, like a bulb...