So i just ordered the asus maximus Vl hero for my new haswell build and im wondering if my current psu will suport haswell as well as its power saving features. The psu i have is an Antec EarthWatts EA650 650W.
As far as I know, your PSU shouldnt have any effect on power saving features. Generally with PSU's, you just need enough power and connectors ;)
Hope this helps,
I found this link
Its a list of supported psu (with source!)
Then this situation is not generally speaking, because Haswell uses some rather advanced hardware level power saving features that require a compliant PSU.
It is confirmed by Antec, though, so you should be fine.