Corsair HX620W 620W Power Supply

PRODUCT: Corsair HX620W
PROD LINK: Corsair’s current offerings.
PRICE: $139.90 @ ZipZoomfly
Price is at the time of testing!


Since the review of this power supply, some interesting observations have been made of Seasonic built power supplies claiming to have three rails.

Below is a picture of the modular interface PCB. This would have you believe that three peripheral connectors and one PCI-e connector were on one rail (labeled 12V3) and the other two peripheral connectors and PCI-e connector were on another rail (12V2.) This would leave one to assume that the 4-pin and 8-pin are on 12V1 perhaps with the main ATX, or the main ATX is on 12V2 with the fewer number of peripheral connectors.

Corsair HX620W 620W

Corsair HX620W 620W

Looking at the Seasonic main PCB inside the Corsair PSU reveals only two rails, labeled 12V1, and 12V2. There is no third rail. This is illustrated well at Hardware Secrets. Although I can not say that these rails are or are not somehow electronically separated in the PSU’s circuitry somewhere, I did find that there was no OCP (over current protection or “limiter”) on either of these rails as I was able to load any given connector up 30 to 40A with no drop in voltage, system shut down, etc.

So it is my opinion that we essentially have a single 12V rail PSU here. Certainly, there is nothing wrong with this given the problems high-end video cards have had with getting enough power from a single 12V rail when the OCP is set to the typical 240VA limit. But we do lose the advantages of multiple rails such as protection from damage to one rail from a short on another and the simple “filtration” of noise introduced from one rail to another.