Author

Topic: PSU with 120/240 switch (Read 84 times)

legendary
Activity: 3808
Merit: 1723
May 05, 2022, 10:00:13 PM
#7
Yeah those voltage switches sure brings back memories of when I was building computers as a kid. Then I saw that PSU never came with those switches. The PSU automatically detects the voltage and automatically switches.

I actually for fun tried mining with those silver box OEM PSU. It actually worked but efficiency was horrible. From the wall it used 300 watts but only actually 200 watts to the rig. And after maybe a day or two it stopped working all together. So definitely can’t use them for mining.
legendary
Activity: 1834
Merit: 1136
May 04, 2022, 11:48:28 AM
#6
Thanks for the response, I thought there may be a newer PSU with such a switch today, so generally all PSU can work with 120v and 240v out of the box, that's wonderful, I do have a old dell power supply with such switch and I still use it for my gaming PC, I was just curious to know.
There are a lot of problems with this switch. Many users set this switch to 110 on a 220 volt network, and the power supply immediately broke. Therefore, in modern power supplies, this process is automated, the minimum and maximum voltages are written in the instructions.
full member
Activity: 182
Merit: 152
May 03, 2022, 10:55:35 AM
#5
Thanks for the response, I thought there may be a newer PSU with such a switch today, so generally all PSU can work with 120v and 240v out of the box, that's wonderful, I do have a old dell power supply with such switch and I still use it for my gaming PC, I was just curious to know.
Yeah, don't use that old Dell unit for mining. Every modern ATX PSU will support 100-250v without a switch. There are power supplies like AlphaMiner that support 277 volts, which is very useful for mining warehouses in the U.S. where the three phase voltage is 277v/480v. That way, you don't need to buy expensive transformers to step down to 240v or 208v.
member
Activity: 201
Merit: 31
KUWA.ai
May 03, 2022, 02:22:09 AM
#4
Thanks for the response, I thought there may be a newer PSU with such a switch today, so generally all PSU can work with 120v and 240v out of the box, that's wonderful, I do have a old dell power supply with such switch and I still use it for my gaming PC, I was just curious to know.
member
Activity: 1208
Merit: 27
May 02, 2022, 01:52:06 PM
#3
havent seen them for decade. Now all PSU works in range 85 - 264 no need to switch.
full member
Activity: 182
Merit: 152
May 02, 2022, 10:29:31 AM
#2
The orange '120/240' voltage switch is for power supplies that do not have active PFC (power factor correction). The switch toggles a voltage doubler circuit. Since they don't have PFC, the power factor can be 0.6-0.8, which means that if the active power is 100w, the reactive power can be as high as 167 VA. This requires thicker cables and stresses the utility company's primary-to-secondary transformer.

This is an outdated design that is over 10 years old. Some OEM's like HP/Dell don't care because these older PSUs can be cheaper for them to buy in bulk, and a Dell Optiplex uses < 200w anyway. Never buy a PSU with a voltage switch, especially for mining. The minimum requirement should be active PFC, 80+ Bronze and 18AWG or thicker wires for the PCIe cables. I always buy 80+ Gold, though.

Power supply with the switch: Raidmax XT. Do not buy!

Here's a list of power supplies I would consider: 80+ Gold or higher

I also like server power supplies like the HP DPS-750AB/RB or a few Dell ones that breakout boards can be found for.
member
Activity: 201
Merit: 31
KUWA.ai
May 02, 2022, 05:10:47 AM
#1
Why is it that only OEM power supplies have the 120v/240v switch on them or have you seen a Corsair PSU with such a switch? If you have seen any PSU with this switch that isn't OEM PSU please share me the details where I can find and buy them.
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