voltage rails from speedfan

[hkivan]

Hi guys,

I checked the 3 rails from my PSU by a DMM.
They were OK. I ran 3Dmark 05 & saw the values
from the chart of speedfan.
The voltages varied between :
Vcore : 1.62 to 1.57
+3.3v : 3.26 to 3.21
+5v : 4.92 to 4.89
+12v : 11.5 to 11.37 .

The voltage fluctuations are 50mv, 50mv, 30mv and 130mv
respectively.

The 12v rail was at 12.4V from a DMM reading while it
shown by speedfan was 11.4v .
I know software readings are not accurate
but can you guys tell me if the voltage chart of speedfan
can be trusted ?

From some PSU sites, I saw they quote their PSUs
have ripple & noise on different rails, e.g.,
50mv ripple on 3.3v & 5v and 120mv
on 12v , 100mv noise on 3.3v & 5v and 200mv on 12v.
In my case, what are the ripple voltages and noise on
different rails?

[willawake]

Re: voltage rails from speedfan

but can you guys tell me if the voltage chart of speedfan
can be trusted ?

nope trust in dmm readings under load. a clamp meter is useful.

[hkivan]

Re: voltage rails from speedfan

Willawake, You mean the fluctuations shown on
speedfan were not reliable?
I just want to see the ripple & noise of the rails under load.
I wish I could have a CRO to see them clearly!
Can u show me a picture of the clamp meter you mentioned?

[tiresias]

Re: voltage rails from speedfan

Willawake, You mean the fluctuations shown on
speedfan were not reliable?
I just want to see the ripple & noise of the rails under load.
I wish I could have a CRO to see them clearly!
Can u show me a picture of the clamp meter you mentioned?

Heh... this is where I'm allowed to step in and brag about my Fluke 337

It's just perfect for measuring current draw on your various rails - or the AC input for that matter. For assessing ripple or noise, of course, you will need an oscilloscope.

As for speedfan - it's a very useful piece of software, particularly for PWM/fan regulation, but any voltage measurements are going to be entirely dependent on your motherboard's sensors - which are rarely reliable enough to give anything more than a very rough indication of input voltage.

[Spacedye69]

Re: voltage rails from speedfan

Speedfan is WAY off one one of my ASUS boards, but close on others, so even same mfrs can not be accurate.