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PC Power Supply Discussion Troubleshooting and discussion of computer power supplies

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  #1  
Old 01-09-2018
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Al3xand3r Al3xand3r is offline
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Default 5VSB Rail weakness

In the last time i've looked at that particular aspect of the PSU's. And I found that many of them (more than 90%, and even highest end platforms) does have problems with the OCP protection on this particular rail, and if the rated voltage is excedeed the vreg wold go below the ATX limit or the ripple would be sky high.
And I decided to measure myself all the computer where I have acces (included my rigs) this rail for see the real power consumption, since I not found anywhere at the motherboard manufacturers (and not only) the real power consumption in stand by/deep sleep state, and because on some of PC's have a lot of peripherials wich would consume some power in standby, like illuminated mice and KB, fingerprint scanners, printers, phone chargers etc.

Now, i have 3 possibilities to take the measurments, and I wish to ask all of you wich one would be more precise, and if it worth to take the measurments with the most disturbing one:
1. To make a special power cord for putting my Mastech multimeter directly at high voltage side.
2. To take the measurments directly at the 5vsb rail with the help of an extension cable wich would be simpler to switch with another PC's.
3. To buy a good power meter to measure the power at the wall.

I know that the best option would be the measurment at 5vbs rail (but also the most hard-to-do one) since the current will be higher (1-4 amps) instead of few miliamps wich would be at power cord, and most simpler one would be with the wall powermeter.
Did anyone make measurment in SB with the powermeter? Because I didn't see any accuracy statement from the manufacturers of this devices.
Here are some devices wich I'm thinking to buy.
http://www.floureon.com/product-g_142.html
https://www.amazon.com/P3-P4400-Elec.../dp/B00009MDBU

And wich method you reccomend me guys?
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Old 01-09-2018
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ashiekh ashiekh is offline
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Default

Romania uses 230V, so the units you linked to are not suitable.

Last edited by ashiekh; 01-10-2018 at 03:46 PM.
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Old 01-17-2018
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Al3xand3r Al3xand3r is offline
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Quote:
Romania uses 230V, so the units you linked to are not suitable.
Yes, I didn't look on that aspect, since I was more precupated to find the accuracy of the powermeter.
Anyway the best method it would be to buy a ATX extension cable and to put the multimeter in series with the 5VSB wire. In that way would be a more precise measurment with pure value of that particular rail not influenced by the AC-DC conversion eff. Simply I need to multiply the voltage with the amps and thats it.
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Old 01-18-2018
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ashiekh ashiekh is offline
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Quote:
Originally Posted by Al3xand3r View Post
Yes, I didn't look on that aspect, since I was more precupated to find the accuracy of the powermeter.
Anyway the best method it would be to buy a ATX extension cable and to put the multimeter in series with the 5VSB wire. In that way would be a more precise measurment with pure value of that particular rail not influenced by the AC-DC conversion eff. Simply I need to multiply the voltage with the amps and thats it.
Since an ATX extension cable is less than $2 on eBay, that would be a good way to go.
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Old 01-18-2018
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Yes, but is the most complicated from all variants mentioned defore because would mean I need to open the case in order to take measurments.
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Old 01-18-2018
mariush mariush is offline
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Default

Most of those power meters are only accurate from around 2 watts and up. Other than that sure you can use those.

To measure the stand-by power your system consumes, buy a clampmeter with DC current capability and put the clamp around the 5v stand by wire in the 24pin atx connector or just buy a 24pin extension cable / 24 pin to 20+4 pin adapter cable and cut the 5v stand-by wire in the middle to attach your multimeter probes there.

Do keep in mind that the efficiency of the 5v stand-by circuit can vary quite a lot, from around 65% at a few mA to maybe 85% at 2A+ so that will also affect things.
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  #7  
Old 01-22-2018
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Definitley the way to go is with the ATX extension cable and a multimeter since I will have the most precise measurment and is not much more to-do than with clampmeter, and the latter will not offer the same acurracy.
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