If I was wanting to start off running one of these and then add on one or potentially two with the option of undervolting when desired would it be worth it to get a serious PSU upfront or just buy ATX PSUs and as needed?
We will know more after we see the underclock. Phil mentioned Tuesday he get's his miner so hopefully around then we see a miner with underclock input on input voltage.
I don't think having a ATX psu or server PSU around is a bad thing. For me I had one laying around so I used it, always nice when you have one already. If you buy quality it will last multiple generations. Only suggestion I have is look at deals of ATX psu's and then server PSU's a lot of time server PSU's are cheaper anymore.