How to see whether PS is under powered?

ugh

Platinum Member
Feb 6, 2000
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Hi all,

Is there an sign which I can see to determine whether the PS is under stressed from powering the components?
 

sohcrates

Diamond Member
Sep 19, 2000
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I think the most obvious sign would be if you are having weird problems like random restarts or trouble turning the computer on.

Other than that, if you have some sort of monitoring utility, like motherboard monitor 5, you can view your voltage levels from the PSU and see if they are fluctuating too much
 

ugh

Platinum Member
Feb 6, 2000
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<< I think the most obvious sign would be if you are having weird problems like random restarts or trouble turning the computer on.Other than that, if you have some sort of monitoring utility, like motherboard monitor 5, you can view your voltage levels from the PSU and see if they are fluctuating too much >>


Oops, should have made my post a bit clearer. What I really want to ask is what kind of weird voltage fluctuations will I see if the PSU is under stressed... Thanks for the info BTW.
 

sohcrates

Diamond Member
Sep 19, 2000
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<< . What I really want to ask is what kind of weird voltage fluctuations will I see if the PSU is under stressed... Thanks for the info BTW. >>



Yeah, that's a good question.

I've picked up bits and pieces of what people say recently...and the best i can tell you is that the +5 volt line should probably not go below 4.9 or so.

I'm really not too sure any of the other lines...hopefully someone could enlighten us both :)

 

ugh

Platinum Member
Feb 6, 2000
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<< I've picked up bits and pieces of what people say recently...and the best i can tell you is that the +5 volt line should probably not go below 4.9 or so. >>


IC. I guess I'm safe then. But somehow the 5v line is around 5.05 and the Vcore line is like 0.03 - 0.05 higher than the value set in the BIOS. I don't feel safe there.



<< I'm really not too sure any of the other lines...hopefully someone could enlighten us both :) >>


Any PS gurus out there? :)
 

Wind

Diamond Member
Jul 22, 2001
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It is normal for most mobo to add 0.05v to 0.1v to the set vcore for stability purpose. Ur vcore reading is normal.

Severe underpower PSU will caused system to reboot/hanged. A mere sufficient PSU will keep the system running but the 5v rail will drop during f/load. Generally, most system will hanged if the 5v rail drop lower than 4.6v. Stability normally return at 4.7v.
 

ugh

Platinum Member
Feb 6, 2000
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<< It is normal for most mobo to add 0.05v to 0.1v to the set vcore for stability purpose. Ur vcore reading is normal. >>


IC. So I guess my mobo is still not faulty :D



<< Severe underpower PSU will caused system to reboot/hanged. A mere sufficient PSU will keep the system running but the 5v rail will drop during f/load. Generally, most system will hanged if the 5v rail drop lower than 4.6v. Stability normally return at 4.7v. >>


What you're saying is that the 5v rail is some kind of benchmark of how well the PS is doing?
 

Wind

Diamond Member
Jul 22, 2001
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<< What you're saying is that the 5v rail is some kind of benchmark of how well the PS is doing? >>


Normally the 5v rail is the most apparent evidence relating to PSU issue.
 

cookieman

Senior member
Jun 12, 2001
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Wind is right!

What you can do further is to install MBM and log everithing down. Try to stress your system (CD/DVD/HDD and all of your componenst )
and aim to idle/full load your system as fast as you can.
From logs you'll see the lowest 5V/3V/12V rails values.

Cheers,
 

Yoshi

Golden Member
Nov 6, 1999
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I have an Asus board and was using their software to check CPU temp and voltages. With my old 300W supply I noticed a lot of voltage instability on all the the taps (Antec 300W supply). I never suffered any system instability due to this, as a matter of fact I had my doubts as to the accuracy of the software. Seeing all those radical changes in voltage without any crashes was a bit of a mystery. I recently installed a beefy Antec 400 watt supply anticipating a CPU upgrade sometime in the near future, my old 300W is not approved for use with P4 or any of AMD's high speed Athlons. Put that baby in and BAM, according to my software all the voltage taps are rock solid stable, virtually no fluctuation what-so-ever.

In conclusion, I guess voltage fluctuation does not mean too much. Mine used to change a lot but did not seem to cause overall system instability.
 

Wind

Diamond Member
Jul 22, 2001
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<< I have an Asus board and was using their software to check CPU temp and voltages. With my old 300W supply I noticed a lot of voltage instability on all the the taps (Antec 300W supply). I never suffered any system instability due to this, as a matter of fact I had my doubts as to the accuracy of the software. Seeing all those radical changes in voltage without any crashes was a bit of a mystery. I recently installed a beefy Antec 400 watt supply anticipating a CPU upgrade sometime in the near future, my old 300W is not approved for use with P4 or any of AMD's high speed Athlons. Put that baby in and BAM, according to my software all the voltage taps are rock solid stable, virtually no fluctuation what-so-ever.

In conclusion, I guess voltage fluctuation does not mean too much. Mine used to change a lot but did not seem to cause overall system instability.
>>


Do ur 5v rail drop ever below 4.6v ?
 

Wind

Diamond Member
Jul 22, 2001
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<< Before the new PS I would get momentary drops below 4 volts!! >>


& ur system is stable ?
 

MilkPowderR

Banned
Mar 30, 2001
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His may be stable with +5V fluctuating less than 4.6 if he isn't running any programs hard. If the user is just in windows doing nothing at idle, almost any voltage fluctuations as low as 3.1V from the +5V would still may run. So yes, it is not considered Stable to run anything harder i.e. using photoshop, some intensive office apps, playing heavy games, and especially in the CPU burn/testing programs. I have to mention this because a lot of people(not just anandtech forum) from the all other sites throughout the net think their machine is stable even though the voltages fluctuate severly. Testing for stability only counts when the CPU and the rest of system is put under max load, stressing them to death.
 

cookieman

Senior member
Jun 12, 2001
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MilkPowderR you are right,...

Everybody thinks their system are stable just running Prime & other testing prgs....
Stress everithing in your system at once (including Sound/CD/DVD/...) you see your voltage fluctuating and system being unstable.

Cheers,
 

vlieps

Senior member
Jun 15, 2000
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Do not see the point in this, what do you need - to make your system unstable or work on your computer ?

Why on this planet earth would one want by all unnatural means to make the system unstable. If everything runs fine, thats it - if you have problem, you solve it, you do not look for problems without reason.
 

cookieman

Senior member
Jun 12, 2001
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vlieps: I can see you do not get it....

Let's take as example me:
Well sometimes I use my system to capture from my TVTunner card.
You see, I allways capture in DivX format (CPU intensive), and the sound in Wav. So I have the SoundCard/Hdd/TvTunner/CPU/PSU/PCI bus/Memory... running pretty much loaded sometime for hours... Sometimes in the same time I make some Audio/Video conversion/compression in the background on some other movie, stressing everything to the max (my CPU can take it, and I do not drop frames....).
And there came the surprise, the system (wich ran extremely beautifuly all the time) could not take it...

Do you think that just testing with Prime will give me some stability results that are at least half true ?

My testings convinced me that just with Prime you get nothing tested (well except the CPU and it's cache). Period.
I was not testing just for the fun to make my sytem unstable. It came to me that running Games/or coding around was stable but as soon as I get to the TVCapturing had crashed on me (between 5-minutes or 3 hours). I would not call such a system stable.

Now my system it's stable. And not just in Idle....
I will laugh in the face of anyone that call a system running Prime without erros, stable. It might be...

Do not take it personaly. Thank you.

Cheers,
 

Wind

Diamond Member
Jul 22, 2001
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I doubt tht any system could run stable if the 5v rail drop below 4.6...4.5 the most. Yoshi, I would like to have some info on how u ran ur system stable...& i mean stable as in f/load w/ 5v rail lower than 4.0v !

Await ur reply.
 

ugh

Platinum Member
Feb 6, 2000
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Just a short question, how's a good way to totally stress out the system besides running those benchies like RC5 or Prime5?

Is copying CD content to Hard disk back and forth while compressing audio/video a good measure?