Thank you all for the info. Very valuable for noobs like myself.

Just to make sure I understand it correctly; I run dedicated 30 amp 240v w/10 awg line with l6 30p outlet. I buy pdu rated 30 amp with l6 30p  (24 de rated ) like the APC 9571A and I am good for 5k watt right?

My circuit breaker has  2 spaces empty next to each other but I am not sure what is the total power coming in to the house.

Also, standard ATX psu in the US is rated to use 240v ? I know that all my three rigs are hooked to 120v outlets right now.