Speakers Not Recognised

Hi All

Been a while since I was last on.
Got given a system from one of the old boys I work along side.

Intel i7 - 3930k @ 3.2GHz
31.94 GB RAM
Sabertooth X79 motherboard
GTX 460 graphics (I know, its going to be the first upgrade when I can afford it)

Missing a power supply & hard drive. Got both installed easy enough, Win 10, drivers etc running a charm. Except I can not get sound.

Logitech Z200 (3.5mm jack, mains power)

System just will not register speakers. Says not plugged in.
Uninstalled & reinstalled drivers,
Restarted Windows Audio & Audio endpoint,
Reinstalled graphics card,
Ran trouble shooter,
Re installed Motherboard Audio drivers.
And yes I did check they work on a different machine (Dell laptop, i5, win 10)

I am at a loss as to what is stopping my speakers working, same thing happened on the last PC when I "upgraded" to Win 10, but that time I put it down to old speakers (not these ones) & old system (Core 2 duo). Please I am looking for any help possible.