You can run more than 1 psu on the same system, use an Adaptor splitter Cable Connector
so you can use both psu.

As a noob myself, knowing very little about crypto mining I tried minergate, ran it for a few days
and it stayed on unconfirmed earnings, so had a look around and found this forum
which had thread about it, some suggesting it may be a scam others not.

I kept away from nicehash because of the Hack.

So I switched to betterhash, windows64 based GUI, download and run, very easy to get going as an newcomer.
Well worth a look.

In the meantime i'm reading alot trying to learn before I jump in the deep end.

Loads of knowledge here, just take the time an make an effort to find what yer looking for.