PCIe, How does the Bios Know?

when the slot is empty there isn't a complete circuit, when a card is in the slot the circuit is made complete and lights flash, go-go dancers kick and the bios goes. OH there is a card in that thurr slot

 

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While Michela Joy's answer is probably the most accurate, EFA11's is more fun to read and gets the basic concept right.

 

@Myrrh: So true

 

Because that is the job of the BIOS, to detect hardware

 

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@catgirl: EFA's answer popped in about 2 seconds before I posted my reply.

I admit that the reading is a bit dry, but that Wiki pretty much describes what's going on.

And MrMagic is right; The BIOS interrogates each piece of hardware on the local bus and determines how to set it up, based on the card reply. How the hardware responds should be in that Wiki. At the very least, you should be able to find a thread describing the response of the hardware to the BIOS. But you don't need that info, unless you're troubleshooting a PCI card at the chip level. Then, you'd stick a logic analyzer on the local bus and watch for the burst.
(Been there...done that )

Just curious. Are you learning hardware design?

 

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BIOS is also programmed to read the hardware ID and list exactly what make/model hardware you have inserted, it's specs / default clocks / voltage / timings, and set them accordingly

As long as the BIOS has been updated to support said hardware

 

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unless its an old G31m pci-e v1 and the amd R9 is pci-e v2 and shows all subsystem ids 0000 on post screen (intel i7 coming soon)

 

Been changing out PCIe cards for days looking for this phenom... any special card I need to look for?

 

I have an old X1600 Pro that has a picture of a lady on it... Maybe you need to try one of those?

 

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