Navagon: Is what you're saying regarding UEFI motherboards then? Because that's the only sense I can make of this. Older motherboards would just beep. There's even a set number of beeps for an improperly powered GPU.
I don't know if this is the case for UEFI as I haven't had any cause to check. But I wouldn't take it as a given that the OP has one. Even now they're not universal.
It is true that there is a bunch of GPU and power related POST beep codes, but they are rather meant to indicate a hardware or power supply problem, as in, an actual defective piece of hardware. In other words, an unplugged external power cable is not classified as a POST error (it is possible to distinguish that fact from a defect). But for example, a card that has not been properly fitted into the PCI-E slot would cause a beep.
That being said, I've never seen an ATI/AMD card in that state before, I am only familiar with the internals of NVIDIA GPUs. I think a manufacturer could in theory set their hardware to fail the POST if they wanted, but there is no technical necessity to do so, and it would not be as user friendly as a simple pop-up warning, so I don't see why they would do that.
Okay, now we are really getting derailed :)
