Ranges for the 12V rail

[jnick]

While looking in speedfan yesterday, I noticed my 12V rail was changing between 12.52 - 12.65. Me knowing nothing about rails and how much they should be carrying, are my numbers to high?

Thanks

 

[ChingChang]

That should be fine

ATX specification requires the voltage to be within +/- 5%
so the minimum should be no less than +11.4v
and the max should be at most +12.6v

though, your voltages *could* be spiking much higher/lower if your measurements are inaccurate, in which case you might have a problem

Which power supply are you using?

 

[E4g1e]

While looking in speedfan yesterday, I noticed my 12V rail was changing between 12.52 - 12.65. Me knowing nothing about rails and how much they should be carrying, are my numbers to high?

Unfortunately, Speedfan (and other monitoring software) goes only by what the motherboard sensor detects. And the motherboard sensors themselves can be as much as 15% off on the readings. (For example, my rig read only 11.71V on the +12V rail in software - but actually reads 12.11V on a digital multimeter.)

 

[jnick]

So then the only "real" way to test it is with a voltage meter?

Btw, I'm using an X-Connect 500W

 

[jonnyGURU]

You can't trust software at all. Get a DMM and plug it into an extra drive Molex and test your voltages. You'll likely find they're completely different then what the software or BIOS is telling you.

 

[jnick]

Where would you suggest I pick a "DMM" up? A place like Radio Shack? How expensive are they?

Thanks .

 

[jonnyGURU]

If you prefer a B&M, I'd suggest an Auto Parts store.

Radio Shack is good, and you'll get a better DMM, but naturally it will cost more. You only need something basic. $5 or $10.

 

[Ice Czar]

short

for reference Basic Spec compliance of 5% is
+12V....11.4V to 12.6V
+5V......4.75V to 5.25V
+3.3V...3.135V to 3.465V

long

closer to the reference value is better than either higher or lower
stuff also doesnt tend to get fried from lower values as much as higher values
anything higher than the 5% range is called an overshoot and that fries most stuff
anything lower is called an undershoot and that makes things unstable


for reference Basic Spec compliance of 5% is
+12V....11.4V to 12.6V
+5V......4.75V to 5.25V
+3.3V...3.135V to 3.465V
but its also a dynamic range
the supply converts power from AC to DC as the load changes from the components
well it also has to keep the reference voltages within the range above while it doing that
so measuring at one point is like watching a single frame in a movie
so logging the voltage is a good idea

that said your BIOS and software is lying to you
what you dont know is by what amount
for that youd need to measure it with a multimeter
cheap ones can be had for $20 or $30 though their accuracy isnt all that much better than the BIOS
they scale up to hundreds of dollars and increasing accuracy

ideally you calibrate your software to a hard measurement (like at idle)
then log till your confident that your within spec at all times

a high reference voltage at idle means that while the supply might be regulating the load within its own parameter,
under some circumstances it could be letting overshoots through
now there are advantages to having a higher reference value if your overclocking
but only if your not allowing overshoots
thats one of the reasons overclockers like supplies with tighter than spec load regulation
so instead of a supply with a range of 5% regulation it has 3% or 1%
and can thus have a higher reference value without letting through overshoots

most components can deal with higher than 5% values and are commonly tested to survive split second 10% values, but these wear on the components

since IC Chips (integrated circuits) vary from pristine to just barely passing the functional test, that means a little "wear" (electromigration) could cause immediate failure or not be noticable degredation for years

more to the point though, the odds are greatly increased for some failure somewhere by the sheer number of IC chips throughout the computer as a whole.
some are behind buffers like the CPU and RAM which have the voltage modified by the motherboards voltage regulation modual, while other lack any buffer at all, like the drives

 

[jnick]

Thanks guys.

 

[vibe]

Any "better" multimeter recommendations?
I doubt I can justify spending over $25, any good values out there?

 

[jonnyGURU]

Go to an auto parts store and spend $10. I'm serious.

Doubles as a dwell meter for points.

 

[davidhammock200]

Walmart has B&D's for $15.