W10 upgrade worked, but it won't accept any video card + no sound.

2 out of my 3 computers were upgraded no issue.

My last one is a 2008 with an Asus P5N-MX with a E8400 processor.

As stated in the title, I was able to complete the upgrade but I have a black screen if I leave a video cards. I swapped many and the video cards are ok. I will get a display if I use the port on the motherboard. Unfortunately, it won't do better than 1024 x 768.

I was able also to install NVIDIA utility and I saw my GT 630 listed in the device managers, it even ran 1920x1080.... until in a reboot it rejected it and uninstalled it. I did the same with my RADEON/AMD card and same result.

Is it enough to conclude that my motherboard is not compatible with W10 or should I try something else?

I'm not sure.

That motherboard uses the nVidia nForce 610i chipset. The latest drivers at Visual Computing Leadership from NVIDIA for it are for Windows 7.

The 32 bit US English version is here:

http://www.nvidia.com/download/drive...px/30521/en-us

There are also drivers for 64 bit:

http://www.nvidia.com/download/drive...px/30520/en-us

You may have to manually install them to get them to go on. (I had to do something like that with a laptop from 2008 with an nVidia chipset and an AMD CPU. Its 8200m g graphics were officialy supported by nVidia for Win 10.)

I'm not sure that it's worthwhile upgrading such a system from Win 7, but I wouldn't bet that it's impossible.

Maybe you try disabling onboard vid in bios and set to always PCI-E slot also in bios.

As I mentioned I have access to various video cards.

NVIDIA didn't work on my ancien motherboard. I didn't try the specific NVIDIA upgrades listed above but I used their utility, with no success.

I also tried an el cheapo RADEON/AMD HD5450 video card. I had issues during the installation but it eventually got through. and it is working fine now. Except one exception; when booting, the BIOS tells me that the previous boot failed and I have to press F1 to continue. Well from there, it goes on with no issue.

So my conclusion is that the video cards were not really at fault but some are more permissive than others. If I would have to do it again with a 3+ yo computer, I would check the compatibility of the motherboard (and other hardware) with W10; ASUS says that my P5N-MX is not.

I'm not sure that it's worthwhile upgrading such a system from Win 7

Agree. But the gadget lover in me won. :)