PC randomly rebooting - 12v rail reports 10.9v?

NeilF

NeilF

NeilF

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My PC has been randomly rebooting for a few weeks and I've been trying to work out the cause.

When it reboots the ASUS Bios (flashed to the latest version) reports:-

ASUS ANTI-SURGE WAS TRIGGERED TO PROTECT YOUR SYSTEM FROM UNSTABLE PSU​

I sat in the BIOS looking at the monitor screen and noticed while I was watching, the 3.3v and 5v values were stable and pretty much spot on. But the 12v value was varying quite a lot... and was around 10.9v to 11.1v. At one point a value of 10.7v appeared.

While I sat there over tens of minutes the value increased upto a value fluctuating around 11.4v.

While in Windows, it I run a CPU burner I the value still fluctuates from say around 11.3v to 11.7v. I have see it report 12v once for a second or two.


Is this fluctating value a good sign the PSU is having problems keeping a stable 12v supply to the motherboard, and possible the GPU etc...


This an EVGA Super NOVA 850W PC Power Supply on an Asus Z97-A motherboard.


My other suspicion was the video card was playing up, but is this hugely varying 12v value a big finger at the PSU? And explains the randomness of it?


EDIT: While running the Windows ASUS app, it shows a graph. Note how up and down the 12v is! And I could a 10.7v reading! Other times its right up near 11.7->12v!

2ccozo9.jpg
 
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bledd. said:
New psu.

I always keep a cheap spare psu in the house (£40 ish)
Click to expand...

I phoned EVGA this afternoon and they were keen to RMA it.

In their words - "A healthy 12v rail should be between 11.4 - 12.6v, stable, and it should not fluctuate rapidly more than .05v"

So given my performance is very different to that, I've got to hope my random reboots are down to the PSU getting worse and worse. Maybe it's dropping really low, simply cutting out, or maybe spiking!?
 
If the BIOS is reporting a low voltage, then there's a good chance it is out of spec. As Jokester says though, it would be nice to know what the true voltage really is.
 
Borealis said:
If the BIOS is reporting a low voltage, then there's a good chance it is out of spec. As Jokester says though, it would be nice to know what the true voltage really is.
Click to expand...

Indeed...

The fact the 3v rail seems spot on (according to the BIOS).... and the 5v too, but the 12v is all over the shop, with values fluctuating by 0.3v or so, and move up and down from below 11v upto 12v seems to suggest it's not happy... Especially when you compare it to what EVGA support said - "A healthy 12v rail should be between 11.4 - 12.6v, stable, and it should not fluctuate rapidly more than .05v"


I believe the 12v supply should basically be static really..!?

Assuming the PSU is producing the 12v rail even half as poorly as it's reading in the BIOS, changing it seems like the best thing. If that doesn't solve the problem... GPU next!
 
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