allowable fluctuations on 3.3 v rail

[daniel49]

Am experiencing some fluctuations apparently as my uguru alarm keeps going off when I game or start up in the mornings.
The error log states errors of 3.19
3.18
3.11
so far, even though the low threshhold by default is set at 3.10.
I have found at this time that setting the threshold to 3.02 seems to keep the alarm from going off ( at least at this time it does) , but am not sure what the allowable range is for this rail and would appreciate some imput. Is + or - 10 % a good rule of thumb?
The psu is a couple of years old now should I just replace it or if slightly dropping that threshhold continues to work will I be ok in that range?

 

[Pens1566]

Standard is +/-10%. So 2.97 to 3.63 is technically ok. Are you measuring it via some software??? That isn't real accurate, should use a DMM.

 

[dBTelos]

Software doesn't give reliable readings, so just toss that info. If you're worried about your system, then measure with a DMM.

 

[Suspicious-Teach8788]

Software is a good way to tell if there are deviations in voltage, but to get an accurage measure, use a DMM. I use software like OCCT to measure the fluctuations when my system is in load for stress testing, but to get a good idea where I am, I stick in the DMM. I believe software is usually right in calculating fluctuations (the delta), but can be wrong when finding the voltage.

 

[daniel49]

well I picked up a faily cheap dmm before work today and tested the 3.3 V rail.

I observed a low of 2.98V and a high of 3.11V through post and going into windows.
for a mean of 3.04 V.
The Dmm accuracy is stated to be .7% on DC.
But it appears I am definately on the low end of acceptable.

Just for fun I also opened Abit EQ up while I had the DMM hooked up.
while the DMM was reading 3.06V the software utility was showing 3.12V.
was curious how close it would be

 

[John]

Originally posted by: Pens1566
Standard is +/-10%. So 2.97 to 3.63 is technically ok. Are you measuring it via some software??? That isn't real accurate, should use a DMM.

It's actually ±5%. See section 4.14

http://www.formfactors.org/developer/specs/atx2_2.pdf

 

[Zepper]

Some PSUs have pots inside that can be used to adjust voltages (some fancy ones even have them available to the otside of the PSU) - up to you if you want to mess around inside your PSU or get a new one. IAC, the meter measured voltage is slightly low - should be ~3.14 to 3.46V.

.bh.

 

[dBTelos]

No need to worry, your voltages are acceptable. And..... you probably aren't putting but a amp or two on that rail.

 

[daniel49]

Originally posted by: dBTelos
No need to worry, your voltages are acceptable. And..... you probably aren't putting but a amp or two on that rail.

I think you are right . but there seems to be a couple of diff trains of thought out there as to wether 5 or 10 % is acceptable.

So I think what I will do is just slightly bump down the uguru alarm and if the voltage degrades any further it should set it off.
And at that point I will replace the PSU.
Have already spotted a coolmax that I like.

 

[Zepper]

The ATX spec is available on http://www.formfactors.org - but it is +/- 5% on the major rails, 10% on the negative rails, not sure about the +5 standby.

.bh.

 

[dBTelos]

The only good/decent coolmax I've seen is the Greenpower. 850W & 1KW, reviewed by Jonny.

 

[daniel49]

Originally posted by: dBTelos
The only good/decent coolmax I've seen is the Greenpower. 850W & 1KW, reviewed by Jonny.

meh, changed my mind and went with seasonic M12 instead.
little more money but I get the sleeved cabling, its modular, and has room for expansion

 

[dBTelos]

IMO, the Corsair is a much, much better deal.