PCI bus conflict apparently causing Win95 lockup

Posted on 1998-07-04
Medium Priority
Last Modified: 2013-12-16
How do I detect a correct an apparent PCI bus conflict which causes Win95 to hang during bootup? I recently added a Creative Labs 3D Blaster Voodoo2 to my system, precipitating this problem. The Diamond Video VRAM card has a know conflict with the 3D Blaster which was supposedly fixed by running a utility (S3fixv2.exe) which apparently changes the values in address registers on one of the cards. After accomplishing the remap operation, the utiltity then spit a message to the effect that the 3D Blaster/Diamond conflict was fixed but that it had detected another PCI bus conflict that is unrelated to the 3D Blaster card. Win95 now hangs with a gray screen after the Windows 95 flag screen disappears! Arrrrrgggggggg!

The only approach that I know of is to tear down the machine and install one board at a time, letting Win95 detect and install it to see where it fails. Bummer!
Question by:rgallaway
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Expert Comment

ID: 1756765
Do you have any other pci cards installed? I would go into device manager and check the memory resources of the all the pci cards to see if you can find a conflict. I would also bitch at Creative Labs since their card and/or utility have apparently rendered your system unusable. That is not a good recommendation for their product - if they didn't help I would return the card.

Expert Comment

ID: 1756766
take a look in the CMOS setup utility.  There is a way to assign interrupts and change other values for the PCI setup.  It is possible that you can do a rebuild or refresh, or even to set the cards up manually.
LVL 17

Expert Comment

ID: 1756767
Have you tried starting in Safe Mode and going into the device manager in control panel and setting the resources manually? You can set a known conflicting device to another address and IRQ and then set your sound card up afterwards.

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Expert Comment

ID: 1756768
I think jrbuck is probably on the right track. Look for a "Reset Configuration" option under PNP or PCI in your CMOS.

Expert Comment

ID: 1756769
i too agree with jrbuck but also you can try going into safe mode and removing all entries for the Voodoo 2 card and the regular video card this will make windows find them again and should set the IRQ's differently.  One other strange thing is normaly the PCI Bus can share IRQ's. (though it is not common for two video cards to share one)

Expert Comment

ID: 1756770
You might try to swap PCI boards around. PCI slots get a IRQ assigned during bootup by the BIOS. I was lucky, my BIOS allows me to specify which slot should use which IRQ. Other BIOS don't allow this. Allthough PCI slots allow IRQ sharing, some boards do not. I have a Adaptec 2930, Matrox Millenium and a NE2000 PCI clone. By default the BIOS set the Adaptec and Nic to share an IRQ. Seemed ok, but windows kept shutting down one of the two (Adaptec seemed to win more).

Set up system so that Nic and video shared IRQ and all problems went away. Most video drivers do not use an IRQ. I had no IRQ's left so this was the only option for me.

Also be sure to exclude any ISA resources in the BIOS. This will prevent the BIOS from assigning these to the PCI slots. You don't need to reserve them in W95, as long as W95 detect the device properly.

Expert Comment

ID: 1756772
Try to see if there is any conflict for memory or irq in device manager. If it is. try to remove or unload the conflicted device. If it is IRQ conflict, try to look for any free IRQ available.
Then, disable (if possible, any setup program) the PNP feature of the device and manually assign the free resources for the devices. If it still doesn't work, try to refresh the BISO setup (use default)  or upgrade BISO. Or try to disble BISO PNP feature if it has. And install the device manually. Lastly, get all the latest drivers for all devices and remove them form device manager, and windows detects them and assign the resources for them.
LVL 14

Accepted Solution

smeebud earned 200 total points
ID: 1756773

This problem is caused by a Plug and Play BIOS that is not supported by Windows 95 on computers that
have a PCI BIOS but not a PCI bus.

On PCI computers, it is the PCI driver that starts the Plug and Play ISA driver. If the PCI driver fails, the ISA
driver is not loaded, and Plug and Play ISA adapters are not automatically recognized or configured.


To add a Plug and Play adapter so that Windows 95 automatically recognizes it, enable the ISA Plug and
Play bus using the following steps:

1.In Control Panel, double-click the Add New Hardware icon, and then click Next.

2.Click No, and then click Next.

3.Click System Devices, and then click Next.

4.Click ISA Plug And Play Bus, and then click Next.

5.Click Finish.

6.When you are prompted to restart your computer, do so.

You may also want to contact your computer manufacturer to inquire about obtaining an updated Plug and
Play BIOS that is supported by Windows 95.


Please tell us all about you system, hardware and software.


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