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How to tell if a PSU is failing.

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WhitehawkEQ

Premium Member
Joined
Dec 6, 2010
If you have a circuit breaker that is tripping every few hours or less, you may have a PSu getting ready to fail. This morning I had a breaker trip twice, I narrowed it down to 1 PC and it happened a few months back on a different PC.
So if you have breakers tripping, and you run a PC 24/7, you may need a new PSU.
 

RJARRRPCGP

Member
Joined
May 30, 2004
Circuit breaker tripping=Most likely a primary-side failure, good chance of there being bad primary filter caps. (The big cap(s) ) (with active PFC, expect just one primary filter cap)
Good chance of there being a bad bridge rectifier. (bridge rectifier that failed shorted instead of open)
 

RJARRRPCGP

Member
Joined
May 30, 2004
A secondary side failure is more likely to result in a fire without any circuit breaker tripping.

A bad 5V-standby cap (secondary filter for 5V-standby I believe) can cause your mouse and keyboard to get fried!
 

UltraTaco

Member
Joined
Oct 28, 2017
Speaking of mouse, mine freezes for like half a second and my drives on taskbar(shortcut) all blink, it happens sort of randomly and often. Sometimes if I unplug mouse and plug back in, problem stops, but sometimes comes back. I unplug power when not using pc.

Wondering if this may have anything to do with PSU going wonky on me. It's '09 something, so fairly recent and its 750 watt, sli rated. Good equipment.
 

Automata

Destroyer of Empires and Use
Joined
May 15, 2006
I've also had UPS units trip breakers. This would depend on what type of breaker it is, though.
 

UltraTaco

Member
Joined
Oct 28, 2017
Agreed, these spark sensing ones get more and more sensitive until they eventually fail. I had one in garage back in fl keep tripping every 20 mins and nothing was even plugged in!
 

MaddMutt

Member
Joined
Jan 12, 2015
Speaking of mouse, mine freezes for like half a second and my drives on taskbar(shortcut) all blink, it happens sort of randomly and often. Sometimes if I unplug mouse and plug back in, problem stops, but sometimes comes back. I unplug power when not using pc.

Which Windows are you using? Win 7 or 10. I had something like that happen with Win 10 and a USB 3.1 7 Port Hub. Every few minutes the computer would lose the HUB and the have to re-find it. This caused everything connected to it to disappear/stop working until re-found :-( I could watch it under ->Control Panel ->Device Manager - USB Controllers as the system lost (the Mouse, Keyboard, Thumb Drives, Ect) and them re-installed them.
I would check this and also update your USB/Chipset/System (AMD/Intel) driver to see if that helps
 

UltraTaco

Member
Joined
Oct 28, 2017
Mr.Mutt, windows 10 and I'll check device manager to see what flickers. Maybe mouse going bad. Or keyboard
 

Nebulous

Señor Senior, Senior
Joined
Oct 11, 2002
Location
The Empire State
My circuit breakers never tripped when I lost a PSU. I knew I lost a PSU when it went boom and let loose the magic genie's smoke. :rofl:
 

ihrsetrdr

Señor Senior Member
Joined
May 17, 2005
Location
High Desert, Calif.
My circuit breakers never tripped when I lost a PSU. I knew I lost a PSU when it went boom and let loose the magic genie's smoke. :rofl:

I had a brand new Gigabyte board let the magic genie smoke out of a mosfet...that was pretty cool! But yea, the board was toast, I bought it from PC Club in town, so I just exchanged it quick-like-a-bunny the same morning.

MOSFET.JPG
 

SPL Tech

Member
Joined
Nov 28, 2006
Specifically what causes the PSU to cause the circuit breaker to trip? Circuit breakers trip when too much current is drawn through them.
 

Automata

Destroyer of Empires and Use
Joined
May 15, 2006
Specifically what causes the PSU to cause the circuit breaker to trip? Circuit breakers trip when too much current is drawn through them.
There are multiple types of breakers. RCD/GFCI breakers will trip for reasons other than high load. As I understand it, if a device on the circuit is leaking current over the threshold of the design (return current is not the same as what it sent), it will trip.

RCD/GFCI, specifically, are a problem with UPS units, because they have inherent leakage.
 

SPL Tech

Member
Joined
Nov 28, 2006
(return current is not the same as what it sent), /QUOTE]

Well that will never happen and it's not supposed to. That phenomena is called power factor. With the exception of purely resistive loads like electrical heaters and incandescent light bulbs, ALL electrical devices return a portion of the current it consumes. The device will draw a certain amount of power and return a smaller amount over and over 60 times per second. That is normal and well-known and it says this on the sticker on the back of your PSU. Yes, if the power factor of an electronic device is low it can cause a circuit breaker to trip because more current is flowing through the breaker. Power consumption is not measured in amps, it's measured in watts and the two do not always scale. A device can use a high amount of current while using a modest amount of power if the power factor is low (e.g. it draws 1000W from the wall, but returns 500W AKA power factor of 0.50).

In any case, the PF of a PSU should be relatively high. The high side caps exist specifically to keep the power factor higher. The more caps you have in line with the input of an electronic device, the higher the PF will be. They actually make building-wide capacitor banks specifically to increase your PF because if your PF is too low the power company will fine you (usually limited only to industrial applications). Electrical motors typically have poor PF rates, consuming far less power than actually drawing, which is why industrial plans with lots of electrical motors will invest in capacitor banks.