I have built a super quite single card headless miners. Gen Ethos for the os. Very little heat and not louder than a regular PC.  Used a Dell Inspiron 530 computer with a Asus R9 380x. Got a free PSU from Amazon after they sent me two when I only paid for one PSU. Computer I got from an electronics recycling dumpster for free.  Total cost for the setup was $50 and that was for the Asus R9 380x off a guy on craigslist. Does about 16 Mh/s for Eth. Not much I know but it's quite as a mouse and little to no heat generated. Since it is headless, no monitor required and I can go to it's ip address and pull up a web interface to see it's stats.