Old PC = New XMR Rigg
When mining Monero XMR, never leave hash on the table.
If you have an old PC laying around you may as well fire it up and tune it to mine Crypto. Below is an old AMD64 single core running DDR2 RAM getting 140 H/s with a single R7 240 running XMR Stak. If you can keep energy cost down and squeeze performance out of an old PC, then u don't need high end GPUs.
New-old Rigg
Now to add some risers and 2 more R7s if it can manage. Only 4gb DDR2 RAM so it's gonna be tricky. If you have any suggestions please comment below.