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Motherboard or modem?

By supportoranges ·
New motherboard refusing to go through POST. Take out modem (GVC Model F-115I/R2F Conexant RS56-PCI chipset based) and mobo and computer work perfectly. Put modem in, mobo doesn't POST. PS is known good. Given everything equal in the two scenarios, how (electrically speaking) can a PCI card prevent a mobo from going through POST. Is it something of a short circuit? Need to know because I don't want to diagnose bad mobos incorrectly.

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by sgt_shultz In reply to Motherboard or modem?

i dunno.if it were me i would try another known good pci card in that slot and i would try the modem in another slot and if that all failed i would blame mb

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by supportoranges In reply to

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by mikex In reply to Motherboard or modem?

Try this - go to BIOS and check any advanced PCI settings - Disable any modem settings and try again

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by supportoranges In reply to

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by TheChas In reply to Motherboard or modem?

If you try the modem in a different slot and it still does not POST, you are at least 90% certain that the modem is bad.

A fried PCI modem is the number one cause of "dead" PCs after a thunderstorm.

If the controller IC on the modem fails such that it locks the data lines on the PCI bus, it can cause a halt state for the CPU and stop the POST process.

Once you verify that the modem is bad, physically destroy the PCI connector and properly dispose of the modem.

Chas

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by supportoranges In reply to

Thank you Chas. As a matter of fact it was after a thunderstorm. I did try the modem in a different slot as you said and it still did not POST.
Thank you also for the explanation. I didn't realize data lines could get "locked" and cause a halt state for the CPU.
I have seen a similar case with a bad disk drive/controller and I always wondered how the POST would stop.
Not knowing this issue I had ordered a new motherboard (perhaps prematurely). Now I need to buy a new modem anyway. Oh well, I guess I should only charge the customer for the modem plus labor.
Thank you so much!

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by supportoranges In reply to Motherboard or modem?

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