What is the recommended processor for mining rigs these days? I have way over powered ones in my older rigs and appreciate suggestions on an intel cpu that will be enough now and going forward.
Cheapest dual-core Celeron with low power usage you can find is plenty for a mining rig, with VERY RARE exceptions.
I'd even say "single-core" but I don't remember the last time I saw a new single-core CPU for sale, don't think anyone makes them any more.
I've got a 3 card R9 290 rig mining ETH on a machine with a Sempron 145 and the only time I notice that the CPU is slow is when it's doing DAG files (LINUX, but I could never get genoil to compile on that machine so it's still running qtminer and rock solid about it - later testing of genoil vs qtminer on a different machine didn't show a significant speed difference anyway, just faster DAG file generation but HAVE to redo the DAG file on every boot).
More than around 300 h/s on a R9 280x seems to require a BIOS mod, as 300 is the best I've managed out of my pair with 1100/1250 (my cards won't do 1500 memory clock at all, and anything other than 1250 gave lower hashrate).
Gigabyte Windforce cards (3 fan versions) running 12.4