question about BIOS processor support

[zeroidea]

I was under the impression that when a BIOS added support for a new CPU, it was just a matter of properly identifying the new processor (since most modern cpu's 'tell' the motherboard what voltage and FSB they need, right?). A recent experience with trying to run a northwood on an i845 board which may not have the latest BIOS installed has prompted me to question this assumption however.. I know that the processor is good, since I bought a different board to run it in, and now I wonder if the other board is dead, or can maybe be flashed with a willamette (something I don't have at the moment)? The power supply and CPU fans would spin when I turned it on, and a motherboard LED would glow, but there wasn't any video or bootscreen.

 

[techfuzz]

The board is most likely not dead it is just not posting because it does not recognize the type of processor and know how to handle it. Motherboard do this to protect themselves from possible faulty/unknown hardware. For example, what if the PowerPC chip had the same number of pins that a P4 has and you plugged the PowerPC in to an motherboard expecting a PowerPC. Well obviously it wouldn't work because the PowerPC is a RISC type processor vs. Intels CISC type. It could possible damage the motherboard in some strange unknown way because of voltage and current through the pins.

techfuzz

 

[tcsenter]

I was under the impression that when a BIOS added support for a new CPU, it was just a matter of properly identifying the new processor (since most modern cpu's 'tell' the motherboard what voltage and FSB they need, right?).

It can depend on each manufacturer's particular implementation of BIOS routines for CPU identification and features/register setup during POST. There are a couple accepted methods to go about this, not all manufacturers use the same method.

 

[Peter]

And of course, there's still the possibility that the board is electrically incapable of using that new processor.