Pretty good deal for a 9590. However, if you don't mind paying for +$100 liquid cooling, a $200 motherboard, a whole load of fans and a beefy power supply, then go forward.
Voltage is what matters for a stable CPU, providing constant voltages and power is down to the quality of your motherboard, how many dedicated power phases it has etc. With high voltage comes heat. Obviously. With something like a H100i GTX, you can even overclock it to 5.2GHz providing that the chip is a good one.
For all of this, you need money. Something that not everyone has a ton of. By getting a 'beast' of a CPU like this, you are wasting a lot of money (both on the short-term and long-term).
Just my advice.