my 5v line wtf is goin on?

my 5v line was at 4.4 under load with my 300w generic psu that came with this case. I went an bought a new 400w antec pp-412x a hour ago, put it in. My 5v is now 4.73 under load. wtf is goin on?!


that psu should have more than enuff juice to power everything. I've heard here and there that you can adjust the voltage to the 5v line by doing somthing inside the psu but don't know exactly what. ANYONE know what my problem could be, how to fix it, or how to mod my psu to give more juice?

Most PSUs dont exactly put out the rated amount of juice. Mine right now in a nonload state is at 4.87v.

I am too lazy to fire up my AMD o/c sysem to tell you what my antec350w reads on the 5v line.


Is the system stable?

the watts doesn't really tell how much juice it will give you.
I beleive you should look at the Amps on the 5v line.
AMD recommand 25, but if you could get 30 amps then it'll be good.

it seems pretty stable, i havent put it thru the run quite yet (only had the psu in for a couple of hours). But i plan on doing a vmod to 2.2-2.4 for the chip and riggin up a vapochill type thing and stickin some 80 or 120mm case fans on. Gonna see bout drillin the holes this week

**Moved post to "Cases and Power Supplies".**

Mr B

This jab is not aimed only at you, but doesn't anyone read posts in this forum other than their own. I swear I have covered this two or three times in the past week. The +5V that reaches your motherboard monitoring circuit, when the CPU is under load, is never the same as what your PSU is putting out. Your PSU may be putting out 5.1V and you can still only read 4.7V or worse on the motherboard. The problem is in the path between the PSU output and the core voltage regulator input.

Read through this thread, especially my several posts.

http://forums.overclockers.ws/vb/showthread.php?s=&threadid=51160

73, Hoot

Thanks Hoot, you beat me to it.

You're a "Life Saver"

Actually, both effects apply. How would you then explain that the 300W PSU got 4.4V while the 400W got 4.7V?

One of the parameters of power supplies is the internal resistance (i'm not sure this is the exact english term). It is defined by design, and must be as low as possible.
Basically, a 5V power supply can be schematized by a 5V ideal voltage source, followed by a resistor (the internal resistance). Once you draw current from the PSU, the output voltage slightly drops. Then line losses produce further drop.

Your PSU will produce a slightly lower voltage under load at its output. The ATX specification requires than the minimum voltage of the 5V line (at PSU output), under the max load specified by the PSU mfg, being equal to or greater than 4.75V (-5% from 5V).

If you already have voltage drop on the 5V line, you may think twice for the vmod to 2.2V. This will increase CPU current draw, which is taken from the 5V ...

Have you ever opened a PSU? They still use insertion components, and ~99% of them use the TL494, an old PWM controller. Amazing to see these dinosaurs barely evolving among our high-tech hardware!