?what is this? "3.3v and 5v lines"

[NewCompGeek]

i hear it when its talked about PSU but i dont know what it is or what it means.

Can anybody explain it to me plz

 

[jcmkk]

if you look at the wires coming out of your PSU you will see three main colors of wire. The black is the ground the yellow is 12v and the red is 5v. I don't remember what color the 3.3v is, but it only goes to your motherboard anyway so you don't really have to worry about it.

 

[Mday]

aside from what jcmkk has said...

basically components in your motherboard require different voltages. the motherboard also has onboard components which alter the voltages for certain components. furthermore, certain voltages act as a signal allowing you to turn the modern PC on and off. this phenomenon is called soft-on\off, where your PC is not really OFF when you press the power button, it is only off when you unplug your computer.

lines just refer to the conductor (generally) as in the wire...

--

things has changed so much, but basically the 3.3v was used to power the CPU (current CPUs require much less energy) and the 5VDC was for other parts of the system (along with other voltages). the motherboard and components use the "lines" as power and as a signal source. without those individual voltages, the motherboard would not know what to do, nor would components which interact with the motherboard.

--
an application of that 5VDC line...
recall that i spoke of soft-on\off... well when you press hte power switch of a modern pc, as in one made during the past few years... the motherboard is constently sent a 5V signal. this is why your system is never really off. when you press your power switch... what you are doing is depressing a momentary switch (a switch that is only closed when you hold it down) and it completes a circuit which sends that 5 VDC to another part of your motherboard telling it to turn on. when you power off your computer, "start - shut down - shut down" the computer sends another signal to the motherboard telling it to power off components.

some find soft-on an annoyance due to the constant 5VDC line being fed to the motherboard. but i will say that the convenience of soft-off is a benefit.

while soft-off can be disabled, the soft-on is permanent, and part of ATX specifications.

remember that back in the days of AT, turning your computer on and off meant closing an opening a circuit containing the 120V (US) directly, as opposed to soft-on where you are only closing a circuit with 5 VDC. huge difference.

 

[Texun]

Regarding the 3.3v part of your question:

I am almost positive the Video card requires 3.3v as does the DDR memory. My MB monitor showed a drop in the 3.3 lead and my video went screwy. Swapped the PSU and the video cleared up and my 3.3 is not 3.3 again. Older memory, I think early DIMM's, used 5v.

R

 

[eplebnista]

Here is a link to an ATX Power Supply FAQ page.

hth,
eplebnista