standard 120v PSU into 240v?

sutheksuthek Member Posts: 255 ✭✭
I have a Corsair HX1000i and it's currently plugged into a 120v circuit.

However, I see the sticker on the power supply states "110 - 240v".

What confuses me though is that older power supplies had a little switch on the back that you'd flick to go from 120v to 240v.

How do I wire this into 240v without that switch? And what's the wiring diagram? Both main legs are 120v? And then the 3rd prong is neutral?


  • RedsquirrelRedsquirrel Member Posts: 11
    Some PSUs can handle the full range without a switch. If you convert a circuit in your house or run a new one that is 240v then you would use both hots from the panel as power between two hots is 240 while any hot to neutral is 120. You would not use a neutral, the ground would still be ground.

    This would essentially double your wattage capacity for that outlet as a load that would normally use 10 amps might only use 5 now. (wattage stays the same of course). Just be careful to note that it's 240 and use proper plug type so you can't accidentally put a 120v load into it. You'll also need a UPS that can do 240, which may be hard to find.

    I'm new to mining myself, but I'm probably just going to stick to 120v for simplicity and just run a bunch of 14/3 BX to do a couple split 120v 15a plugs to my rack.
  • wirelessnet2wirelessnet2 Member Posts: 373 ✭✭✭
    @Redsquirrel so you are saying that you would just wire a 120/240 volt power supply as hot/hot/ground instead of hot/neutral/ground?
  • RedsquirrelRedsquirrel Member Posts: 11
    That's correct. Has to be two hots that are separate though obviously. In your electrical panel each breaker is staggered so you would put a double pole breaker which takes up two spaces, so the two hots on that breaker will be 240v. Though you need to check this when you do the install as panels may vary. Basically you can think of the incoming hydro feed as being 240v, but at the transformer there is a centre tap, that is the neutral. So between the two legs of the transformer you get 240v but between any leg and neutral you get 120v. For a dryer or stove you will often see a big plug that has 4 prongs instead of 3, the way this works is that the two side ones are 240, then one of them is neutral and the other is ground. But for a computer you don't need the neutral at all if you go 240v.

    Though if you are not familiar with electrical probably best to get an electrician to help.
  • noobminer001noobminer001 Member Posts: 7
    edited January 10

    I was thinking about this more and wanted to test it. I was under the impression that 110-240VAC labeled on electrical equipment, the 240VAC was for European/Asia standard where its 240VAC Line to Neutral. I wasn't sure how the equipment would handle two 110 hot lines if the equipment is looking for a neutral reference. I can understand if its labelled 240VAC for NA markets only, but I am pretty sure most of the equipment labelled 110-240VAC is intended for NA and EU/AS markets. Have you ever tested this? I am surprised if the PSU doesn't need a neutral reference if you feed it two hot lines (given that they are designed for European/Asia standard of 240VAC line to neutral). How would it complete the circuit? The neutral acts as floating ground or a bonded ground if its connected to Earth ground. Please don't take this as saying you're wrong, I actually want to test this but I don't have an old PSU and haven't got around to buying one but if someone has already tested this, I would like to know.
  • wirelessnet2wirelessnet2 Member Posts: 373 ✭✭✭
    edited January 11
    @noobminer001 That's why I was confused too! But I do know that the two 120v lines are not in phase, so the return current could return along the other hot wire. Some water heaters and whatnot only need two 120v hot lines and a ground. I think it may work...

    I found this
  • sutheksuthek Member Posts: 255 ✭✭
    Anyone brave enough to test it with a power supply?
    best I can tell, the 240v on a PSU is expecting 240 on a single line plus a neutral.
  • wirelessnet2wirelessnet2 Member Posts: 373 ✭✭✭
    edited January 11
    I’ll call EVGA and ask them
    Edit: I called EVGA and asked the technical support if hot-hot-ground should work, and the rep said that as far as he knew that should be a valid and working configuration. I’ll put a 750 P2 to the test sometime (probably not too soon), and if it works I’ll report back.
  • sutheksuthek Member Posts: 255 ✭✭
    I don't trust customer service people. They don't know anything technical.
    I really think it needs the positive and a neutral.... but if someone has an old PSU to test that would be great.
  • sutheksuthek Member Posts: 255 ✭✭
    it might not though.
Sign In or Register to comment.