Does your motherboard have dual 19 pin headers for USB 3.0? If I'm not mistaken you need 1 header per 2 usb3.0 ports.
I can buy any motherboard for it. This will be a new build.
My apologies. I should have stated this before.
Give us some places where you can buy parts in your country and we can help better. Cases available in USA, Canada, UK may not be available where you live.
Sorry. I'm in Cambodia. I can buy from anywhere in the US and have it shipped to my brother's home. A computer savvy nephew will build the machine and set it up for use, as I am not there to do it myself.
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The most important feature for this computer, will be to have 4 USB 3.0 ports on the top / front of the case. The box will be located under a desk. The person using it will need to be able to use up to all 4 ports at once, for various hardware to be connected. He will not be physically able to plug / unplug these items from underneath the desk. He is aging.
So, I guess, I am basically doing a build, starting with the case and working my way inside.