Just mine the altcoins with GPU's,you can sell em for BTC on exchanges....and the resale of GPU's is better & the warranties are MUCH better...up to 3 years
You only need an old dual core CPU & 4 gigs of RAM....get the cards with 4gigs or more of RAM....HDDS need to be 40+gigs.Just get new PSU's to be sure you don't burn up or short your PC out
Mining Bitcoin is gonna be done by BIG farms only VERY soon.....they keep raising the diff.....so let em have it