Odd Disconnections

For the past few months I have been having odd disconnections where there appears to be no pattern or cause to it.

Some days I can go without getting a single disconnection while other days I can get them every minute for a while. Sometimes the computer will regain connection just afterwards while other times it can take 30 seconds to recover or I have to re-plug my powerline adapter.

I have tried various diagnostics like changing the powerline adapter to another plug or another wall socket. I have tried changing cables from cat 6 to 5. I have swapped between my onboard nic connector and a dedicated nic card with the same result. I have even got an electrician out to swap out the wall socket's face plate.

I am beginning to think that it is the motherboard at the route of all this and some aspect of it is on its way out.

I am currently saving for a new computer (because of this issue) but I would like to resolve it. I do understand though that some problems can't be resolved and the only solution is new hardware.

This is the second time I've had to write this post due to a disconnection.

Thing is that none of the other computers in the house have this problem. I check them while I'm disconnected.

What aspects would be common to both of them?

I've just updated the driver to the nic card going from version 9 to 10 (published this year) but it still disconnects.

Yes I've disabled the power management on the nic card.

EDIT: I've just switched from 1gb full duplex to 100mb full duplex testing to see if it gets overloaded.