PL1000 No Ethernet Light

It isn't clear of you are mixing PL1000 and PL500 plugs. But if you are adding new plugs to an existing powerline network, then you should follow these instructions:

Adding a powerline adapter to an existing powerline network | Answer | NETGEAR Support

As that says, this is the issue that you need to sort out:

When you purchase a Powerline bundle, the 2 Powerline adapters come pre-configured with matching security encryption keys, so they will automatically sync up when plugged into your home network. But once you have an existing Powerline network, how do you add more Powerline adapters to the network? You can use the steps below to add additional Powerline adapters to your network.

If that isn't the problem, it is easier to setup a powerline system if you have the "source" and "extension" plugs in the same room during setup. Then move the extension to its intended location.

As to the motherboard, it should make a difference, but new boards rarely arrive with the latest drivers, especially at the chipset level, which is where the network stuff comes in. Check the maker's website for the latest chipset drivers.

Does the PC do the Internet without going anywhere near the plugs?