# No need of 3.3v line



## JunkBear (Oct 5, 2013)

It may not be new to many of you but I read after quick search that the 3.3v on the sata connectors were originally made to be for hot-swap HDD and for less energy cost and heat. The thing is that it seem that only the psu manufacturers followed and the parts builders didn't. Except maybe for some 1.8" SSD the rest all work without that 3.3v so that's no brainer. That's why it works always when using molex to sata connector that has no 3.3v line. 
When I started to think about it I was sure that the 3.3v sata was for standby mode and low energy use when hdd is not really spinning.

 I guess I was wrong. 

Giving your opinion will be appreciated.


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## JunkBear (Oct 11, 2013)

Bump for some help or any advice.


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## Deleted member 3 (Oct 11, 2013)

What kind of help or advice are you looking for exactly?

Like you said, everything works with a converter and thus 3.3v isn't a requirement.


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## JunkBear (Oct 11, 2013)

Ok so I was right then. It will surely help me with further custom builds. Thx.


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## Frick (Oct 11, 2013)

JunkBear said:


> Ok so I was right then. It will surely help me with further custom builds. Thx.



Why? You do not want to dig around in the PSU.


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## JunkBear (Oct 11, 2013)

I do sometimes in older builds that only have molex stuff. I cut the 3.3v line and plug fans to it for low rpm silent cooling.


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## bencrutz (Oct 11, 2013)

JunkBear said:


> I do sometimes in older builds that only have molex stuff. I cut the 3.3v line and plug fans to it for low rpm silent cooling.



wow, i didn't know you can do that. i always thought 5V is the minimum, heck, some 'heavy weight' delta / sanyo san ace 12V fans won't even kick in with only 5V.


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## JunkBear (Oct 11, 2013)

You can do it with Antec 80mm fans. You just need to look for the serial number because they have Low speed fans, medium speed and High speed for some applications and older power supplies. I take my fans from there most of the time. Basically they all the same except for the internal resistance that change. The higher the resistance = the lower the rpm. If you take High speed model they turn fast and noisy at 12 volts it means they don't have much resistance inside so you can say that they are virtually 3 speed fans. The high speed model dont need a lot of voltage to start spinning so you can start really low at 3.3v, then put medium at 5v and high speed at 12v.  Hoping I am clear on this one.


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## Vario (Oct 12, 2013)

JunkBear said:


> You can do it with Antec 80mm fans. You just need to look for the serial number because they have Low speed fans, medium speed and High speed for some applications and older power supplies. I take my fans from there most of the time. Basically they all the same except for the internal resistance that change. The higher the resistance = the lower the rpm. If you take High speed model they turn fast and noisy at 12 volts it means they don't have much resistance inside so you can say that they are virtually 3 speed fans. The high speed model dont need a lot of voltage to start spinning so you can start really low at 3.3v, then put medium at 5v and high speed at 12v.  Hoping I am clear on this one.



You can also use the 12 and 5 lines to make a 7 volt fan, this is a good option with server fans like san ace denki.


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## JunkBear (Oct 12, 2013)

Not a good idea because it is bridging 2 different sources of current. The psu of computer is not made to self-adjust the voltage in output wires. It will be forcing the 12 volts to downgrade. In my opinion from past experience same as bridging car audio output on amp. But I could be wrong.


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## de.das.dude (Oct 12, 2013)

JunkBear said:


> Ok so I was right then. It will surely help me with further custom builds. Thx.



but the 3.3V is very important. a lof of ICs work on the 3.3V including onboard NIC if any.
so dont just chop it off. XD


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## de.das.dude (Oct 12, 2013)

JunkBear said:


> Not a good idea because it is bridging 2 different sources of current. The psu of computer is not made to self-adjust the voltage in output wires. It will be forcing the 12 volts to downgrade. In my opinion from past experience same as bridging car audio output on amp. But I could be wrong.



the psu in computers IS infact made to self adjust the voltage. unless you are using non-smps ones.

why not just use a zener diode or resistor to get lower voltages.


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## JunkBear (Oct 12, 2013)

de.das.dude said:


> but the 3.3V is very important. a lof of ICs work on the 3.3V including onboard NIC if any.
> so dont just chop it off. XD



The ones of the main plug 24 pins yeah but the wires of Sata. None of odd or hdd work with the 3.3 so can cut wires of sata if you dont need it. The whole set i usually remove it right at the psu when i dont need it. I usually cut all connectors not needed so it save space and make better airflow in small computer cases.


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