Weak 12 Volt Rail

[unsafesteagle]

Most common causes of 12 Volt Rail falling to 10 volts n below?

 

[Woomack]

It's probably wrong reading, as the PC would shut down or restart. Use a multimeter directly on any 12V cable/plug to check it.

 

[unsafesteagle]

PC would shut down or restart

PC is shutting down and restarting.

 

[Woomack]

Then check another PSU. I had one recently, which was randomly going below 11.5V and then the PC was restarting. Mine was a 5-year Corsair 1200HX.

 

[Nebulous]

Yeah I had several units that were very old (7+ years) and the 12v rail had dropped to 11.2/11.5 and the rigs would restart. I remember having an old Sparkle unit that the 12v rail had 10.2v and the rig still kept chugging along, but then again is was a low budget office machine.

Once the rig starts the On and off, on and off dance because of the low 12v line, it's time to replace it.

 

[unsafesteagle]

The unit is EVGA SuperNova G2 1000 watt.
It took heavy heavy use when I first got it and it's definetly been my go to psu and aged.
Looking it up in Google specs say Intel 4th Gen ready. Lolol

I only first noticed the low 12 volt rail when I removed the aio cooler a few days back.

Disconnecting a bunch of extra fans/pump etc... did minor to no difference in the reported voltage

 

[Nebulous]

I think I have a brand new 1000w G5 in my closet. I got it as a replacement for 2 defective and weak GQ units. ( Don't ever get the GQ!)

 

[unsafesteagle]

I'll recheck wire connections ,
Maybe it got wet filling up coolant pushed it lower

 

[Woomack]

I have older PSUs like Enermax 650W SFX, or Corsair SF450, and they keep ~11.8V under load after ~5-7 years. I'm not sure what is wrong with the Corsair PSU as it's 1200W 80+ Plat unit and was working only in tests, usually not even 50% load and I don't even remember when the fan was spinning (the PSU was cold and low load). Anyway, it has a 10 year warranty and I sent it for RMA a week ago. I also got it on sale for $100 new, so if they replace it, then I get something that is worth $250 right now.
I don't know if anything has changed, but new Corsair, FSP or DeepCool have 12.00V flat in idle and 11.8V under load. I remember that most earlier series were like 12.1-12.2V idle and slightly above 12V under load. Still, all new PSUs (at least from respectable brands) have over and undervoltage protection, so will reset or shut down when it's out of specs.

 

[freeagent]

For me, at 11.1v and under is when my old Corsair and Thermaltakes would shut down. That and a 3.3 at 2.8ish will make it crash too. You could try to move the main power cable around, that may help. But if it spent a lot of time running a system at load, it might be done.

 

[unsafesteagle]

But if it spent a lot of time running a system at load,

I folded a year with that psu including a couple water cooled radeon 290

 

[freeagent]

I folded a year with that psu including a couple water cooled radeon 290

That might do it. I did not get much life out of PSU's when folding on them at the edge.

Edit:

I didn't even get 5 years out of my Corsair.. wont be buying another

 

[Woomack]

I didn't even get 5 years out of my Corsair.. wont be buying another

Corsair SF600/750 are my probably favorite PSU series. No problems at all, and I run them 24/7, almost only in tight ITX builds. I have mixed feelings about their lower series, but higher are pretty much the best you can get.
Most brands that rate their PSUs 80+ Gold or higher maintain good quality. There are exceptions, but I had various brands, even something like Abconcore, which is a clone of Seasonic, but made by someone else, or Montech. I had no problem at all with any 80+ Gold PSU of any brand manufactured in the last 3 years.
That Corsair HX, which failed, was on sale, and it was already discontinued for some time when I bought it. It's like a 7-8 year old model. I forgot I was mining on it for a year on 5 graphics cards 24/7, so that can be a reason

 

[unsafesteagle]

Swapped that Corsair PSU in there altho its not what i purchased it for.
Boots right up no video to enter bios boots fast , prob. gotta clear cmos to get in bios.

HWInfo is reporting near 12 volts now.



I didnt trouble shoot the psu that was removed wire connections etc....
Simple way to verify a tired psu without it being installed in a system?

 

[EarthDog]

Jump it!

 

[rdrash]

like in this image...

 

[EarthDog]

Thats for 2 psus at once, but will work just the same. Here's a pure jumper.

CRJ 24-Pin ATX Power Supply Jumper Bridge Tool https://a.co/d/hE5cfdK

If it's reading outside of atx spec (5%, 11.4-12.6) with a DMM (software can be inaccurate) at idle, don't bother with load and rma/Trash it.

 

[Woomack]

... or simply short green and any black wire on the 24-pin connector ... now good luck finding it on the new series with all black wires
But really, without any load, the PSU may show ~12V. Mine was like 11.90V idle and 11.50V under ~200W load.

 

[unsafesteagle]

I believe i have a psu tester ill post whatever that outputs for now.

 

[freeagent]

So that is before there is a load on it? Looks low to me..