Question Computer won't turn on, PSU seems OK

[kalakala]

Over the past few months my system with an old EVGA G2 550 PSU has been experiencing random reboots. After the ECO mode was switched off the problems appeared to be solved.
Now however the computer no longer turns on - no reaction whatsoever when case pwr btn is pressed. USB ports however do provide power.

I tested the PSU as per this makeuseof article, and all the measured pin voltages look perfectly fine:
1-2) 3.318
4,6) 5.061
9) 5.131
10-11) 12.298
12-13) 3.318
14) -12.000
21-23) 5.061

What's the next reasonable course of action in debugging this?

 

[Ralston18]

Unplug - open the case.

Clean out dust and debris.

Verify by sight and feel that all connectors, cards, RAM, jumpers, and case connections are fully and firmly in place.

Use a bright flashlight to look for signs of damage.

 

[Roland Of Gilead]

Hey there,

It's likely the PSU is failing. It had a good run. It's 8 years old. Time to swap out.

 

[kalakala]

It's likely the PSU is failing. It had a good run. It's 8 years old. Time to swap out.

Is it still possibly failing, even when all the rails appear to be producing OK voltage?

 

[Roland Of Gilead]

Well, it's exhibiting all the regular symptoms a failing PSU would go through. EVGA made some damn fine PSU's back then. The G2 was very good in it's day. Not only that, the potential of the PSU letting go mid-flight, could take another piece of hardware with it. That and it's age are going against it right now.

 

[DSzymborski]

Is it still possibly failing, even when all the rails appear to be producing OK voltage?

Yes. You need an actual load tester to actually test a PSU properly (and an oscilloscope).

 

[kalakala]

Well, it's exhibiting all the regular symptoms a failing PSU would go through. EVGA made some damn fine PSU's back then. The G2 was very good in it's day. Not only that, the potential of the PSU letting go mid-flight, could take another piece of hardware with it. That and it's age are going against it right now.

Cool, cheers. Already have PURE POWER 11 (400W) in a basket ready to go. Might even go as low as 300W, as I took unreasonable advice when building the box, hence the 550W G2. Never saw even 200W pulled from the wall.

Had to make sure it's reasonable to get the replacement now. Will come back once it's here.

 

[Roland Of Gilead]

Cool, cheers. Already have PURE POWER 11 in a basket ready to go. Might even go as low as 300W, as I took unreasonable advice when building the box, hence the 550W G2. Never saw even 200W pulled from the wall.

Had to make sure it's reasonable to get the replacement now. Will come back once it's here.

Wait, list your specs so we can determine better. If this is a gaming rig of any description, then I wouldn't touch a 300w PSU with a bargepole. The motto, here being " Get higher wattage PSU to allow your current system to run well, and have enough headroom to move to a more higher powered system down the line.

 

[kalakala]

Wait, list your specs so we can determine better. If this is a gaming rig of any description, then I wouldn't touch a 300w PSU with a bargepole. The motto, here being " Get higher wattage PSU to allow your current system to run well, and have enough headroom to move to a more higher powered system down the line.

https://pcpartpicker.com/list/r4krwg

The box is mostly a 24/7 server running linux, when it's pulling 50-60W from the wall.
Occasionally it's used also for gaming on windows (dual boot). Then the SSD nor HDDs are not mounted. Soon however another box will be built for gaming, and this will continue running solely as a server. GPU might still be used for Emby/Plex transcoding every now and then.

But I've never seen this setup pull even 200W from the wall.

 

[DSzymborski]

https://pcpartpicker.com/list/r4krwg

The box is mostly a 24/7 server running linux, when it's pulling 50-60W from the wall.
Occasionally it's used also for gaming on windows (dual boot). Then the SSD nor HDDs are not mounted. Soon however another box will be built for gaming, and this will continue running solely as a server. GPU might still be used for Emby/Plex transcoding every now and then.

But I've never seen this setup pull even 200W from the wall.

How are you measuring transient spikes? There's stuff you're not going to measure with a Kill-A-Watt type thing.

You also don't want to go any lower than 400W because you get into junk territory because prices don't scale down like that. A 200W PSU doesn't cost half of what a 400W PSU does because many of the costs of a PSU are the same whether it's a 200W, 500W, or 1500W PSU.

 

[kalakala]

How are you measuring transient spikes? There's stuff you're not going to measure with a Kill-A-Watt type thing.

And that's what I come here for. Excellent point I didn't even realize to consider.

You also don't want to go any lower than 400W because you get into junk territory because prices don't scale down like that.

Even with reputable brands like the one I linked? Note it's not PSU price that wants me to select a lower-wattage unit, but their efficiency at ~50-60W mode that it'll be chugging along most of the time.

Guess 400W it is.

 

[DSzymborski]

And that's what I come here for. Excellent point I didn't even realize to consider.


Even with reputable brands like the one I linked? Note it's not PSU price that wants me to select a lower-wattage unit, but their efficiency at ~50-60W mode that it'll be chugging along most of the time.

Guess 400W it is.

A lot of companies, even good ones, really skimp on those <400W PSUs because the margins are just so awful. So they're either bad values or just objectively horrible.

 

[kalakala]

Update.

Received the PURE POWER 11 (400W), but still no POST. Breadboarded the mobo and removed the CMOS battery - and it booted just fine. So looks like some ASRock boards have similar issues to those affected MSI ones - dead battery causes failure to boot. No battery or an OK one solves it.

However change of PSU did solve the original problem of intermittent random reboots mentioned in the original post. So in the end it were two separate problems I assumed to be stemming from same cause.