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I have a Lenovo ThinkCentre M55 which has an x16 PCIe on the motherboard, but came with a PCIe to PCI adapter installed. I removed the adapter so I could use my x1 PCIe wifi card, but as soon as I plug the card in, the computer refuses to turn on.

It seems as if they've made the motherboard this way intentionally. Is there some way around it?

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1 Answer 1

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The PCIe x16 slot on this computer can only be used for a graphics card.

Check the specifications:

Slot 1: Full length, full height PCI Express x16 (graphics only)
Slot 2: Full length, full height PCI Express x1
Slot 2: Full length, full height 32-bit PCI 2.3 (5v)
Slot 3: Full length, full height 32-bit PCI 2.3 (5v)

This is a chipset limitation. From Intel's Q965 technical specifications:

The Intel Q965 Express chipset contains two separate, mutually exclusive graphics options. Either the GMA 3000 graphics controller (contained within the 82Q965 GMCH) is used, or a PCI Express x16 add-in card can be used. When a PCI Express x16 add-in card is installed, the GMA 3000 graphics controller is disabled.

Effectively, there's a switch inside the northbridge that connects the PCIe lanes to either the internal graphics hardware or the PCIe x16 slot. In order to allow external graphics cards to work, the slot has priority. So by putting a device in the slot, you disconnected the internal graphics, leaving you with no video device.

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Great info. So, if x16 is only for graphics, how is it able to support the PCI adapter that's been plugged into it all its life? I've been successfully running an old PCI wireless G adapter off of that. –  xichael Dec 4 '12 at 20:12
    
Sometimes when you break the rules, it happens to work. Sometimes when you break the rules, it happens to not work. I could speculate why you got away with using the PCI adapter, but I'm as likely to be wrong as right. –  David Schwartz Dec 4 '12 at 20:14
    
Is there any kind of x16 to x1 converter that will allow me to use the x1 PCIe wireless N card that I have? Otherwise, I suppose I'll have to buy a PCI wireless N card. –  xichael Dec 4 '12 at 20:16
    
The rules say no, but whether there exists one that happens to work ... I have no idea. –  David Schwartz Dec 4 '12 at 20:20

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