Effects of a Dying 5v rail?

[Spacecrazy]

Firstly, Hello everyone this will be my 1st post!

Im interested if anyone could help me understand what the 5 volt rail is responsible for, and what peculiarities it would have on a system.

Im especially interested as it would seem this is responsible for multiple soft reboots on my PC, i have ordered a new PSU anyway but am left a little confused as to what has happened to my old PSU.

I have searched around online and found little of use.

FYI my 5 volt rail, is outputing a maximum of 3.28 Volts

 

[Deleted member 185158]

Voltage regulator probably took a dump.
What was the bad psu? Got specs?

 

[eidairaman1]

Sign of things to come.

Its a power on signal too.

ATX - Wikipedia

en.m.wikipedia.org

 

[Spacecrazy]

It was a OCZ ZT series 650 watt, bought new probably 5-6 years old

 

[eidairaman1]

It was a OCZ ZT series 650 watt, bought new probably 5-6 years old

Trash it, grab a seasonic

 

[Spacecrazy]

Already ordered a Corsair replacement... Just was getting some weird behavior

 

[eidairaman1]

Hope the corsair oem is seasonic, cwt or superflower...

 

[Spacecrazy]

I built my PC about 5 years ago, thought i'd buy a better GPU... That was when things took a turn for worst... Started getting soft reboots, i thought i'd bought a dodgy card. But its tested fine in a friends PC..

Whats odd is the new GPU is more efficient than the old one and draws less power. But takes 1x 8 pin intsead of 2x 6pin PCI-E i wondered why the 5 volt rail would effect it in this way

Corsair RM750x 80 PLUS Gold, 750 W Fully Modular ATX Power Supply Unit

This is my replacement

 

[Bill_Bright]

Im interested if anyone could help me understand what the 5 volt rail is responsible for, and what peculiarities it would have on a system.

Too vague a question. +5VDC is used throughout the computer on multiple points on the motherboard, including providing power to your drives, USB ports and more. +5Vsb is the standby voltage that keeps your computer (including DDR4 RAM) alive (but asleep) when simply shutdown.

If the +5VDC was missing, your computer would not boot.

FYI my 5 volt rail, is outputing a maximum of 3.28 Volts

How did you determine that? Note the ATX Form Factor allows for no more than ±5% deviance. So acceptable tolerance maximums are:

12VDC ±5% = 11.4 to 12.6VDC
5VDC ±5% = 4.75 to 5.25VDC
3.3VDC ±5% = 3.14 to 3.47VDC
​

It is not likely your computer would be booting if the +5V output was only 3.28V.

 

[Spacecrazy]

I got the value both from Piriform Speccy and OCCT...

EVERY time i tried the GPU test on OCCT the system would soft reboot, without any crash reports of any kind

Testing the same GPU in a friends Computer completed all OCCT tests without errors

Also im still on DDR3 lol

 

[sneekypeet]

Software is a crap shoot as to if it is correct or not. You are having issues, so I would guess it may be showing where the issue is, but that value holds no merit.

If you own a multi-meter, reading it from the 24-pin (connection at the motherboard) when the system is running will give you a defined acceptable value. If you are not experienced in such things, ask questions so we can help rather than potentially shorting or damaging something.

 

[Spacecrazy]

Its ok thanks, iv already ordered a replacement PSU if by some horrible misfortune the problem persists on the new PSU i'll pick your brains then!
But fingers crossed it wont come to that. I suppose something may have died on the motherboard but god i hope not. Cant afford to replace all the parts lol

 

[DeathtoGnomes]

Corsair RM750x 80 PLUS Gold, 750 W Fully Modular ATX Power Supply Unit

Thats a good choice.

 

[Spacecrazy]

I hope so lol

 

[DeathtoGnomes]

I hope so lol

in my signature is a PSU ratings list and you can search JonnyGuru.

 

[Spacecrazy]

Thank you

 

[eidairaman1]

I built my PC about 5 years ago, thought i'd buy a better GPU... That was when things took a turn for worst... Started getting soft reboots, i thought i'd bought a dodgy card. But its tested fine in a friends PC..

Whats odd is the new GPU is more efficient than the old one and draws less power. But takes 1x 8 pin intsead of 2x 6pin PCI-E i wondered why the 5 volt rail would effect it in this way

Corsair RM750x 80 PLUS Gold, 750 W Fully Modular ATX Power Supply Unit

This is my replacement

You have a good unit

 

[Spacecrazy]

Soooo the new PSU seems to fixed my problems but im still reporting a low 5 volt rail.... anybody have any ideas? motherboard damage? faulty sensor?
its not a huge deal as I want to upgrade to a Ryzen based system this year, but it does seem strange though smh

 

[eidairaman1]

Motherboard/sensor, there is a range and i believe it is +-5%

 

[Spacecrazy]

also it was the 650w version I bought not the 750 hope theres no difference in quality lol

 

[freeagent]

Go into your bios and bring up your voltage screen, then stick your hand in the case and move your ATX 12v plug around, maybe you have a loose fitting plug. I have to do that on my X58 board to get my voltages up high. If I don't my kids cant game on it, voltages sag way too low, at or below max spec. But even after all of that, I can still get my rails to sag really low if I oc just the CPU and bench, or game on it. So in my case, I could also have a mobo issue as well. But for me, I just think my plugs are worn out. My mobo is like a pronstar.. has seen many insertions.

 

[Bill_Bright]

Soooo the new PSU seems to fixed my problems but im still reporting a low 5 volt rail.... anybody have any ideas?

Yes. Ignore it. Those sensors are cheap, very low tech devices that probably cost a few pennies for 100 of them.

If really concerned, and I would not be at this point, get a multimeter and measure the voltages in a hard drive power cable from the power supply. As I noted above, your +5VDC should be between 4.75V and 5.25VDC.

Alternatively, you can get a PSU Tester. I keep one of these in my tool bag for house calls. The advantage of this model is that it has a LCD readout of the voltages. With an actual voltage readout, you have a better chance of detecting a "failing" PSU, or one barely within the required ±5% tolerances (at least with the tester’s internal load). However, none of these testers test for ripple and they only provide a small "dummy load", not a variety of "realistic" loads. So while better than nothing, using one of these testers is not a conclusive test. But in this case, it will show your +5V is probably within allowed tolerances.

BTW, I note again software based hardware monitors are not always very accurate. For one, they rely on those cheap, low tech sensors. Speccy, a popular HW monitor by the makers of CCleaner used to report voltages but was frequently wrong - WAY wrong. For example, on this system it would report my voltages were:

+3.3V = 2.028 V​

+5.0V = 3.367 V​

+12V = 0.048 V​

Clearly, if any of those were true, this computer would not be running. I note Speccy had so many complaints about that, they no longer report on those voltages.

 

[Spacecrazy]

Yeah its the OCCT test that reports the low rail. But the system seems stable now i just have to run WarThunder and T.A.B.S to make sure, but i can run all the OCCT tests now without errors. There is a possibility that my motherboard has sagged as the cooler is rather heavy. As a precaution i'll lay the tower on its side. I hope to upgrade to Ryzen 3600 this year when i can afford it! This computer has served me quite well actually

 

[delshay]

Does modern motherboards have the ability to switch the 5v USB to 5Vsb? Suppose you want to charge something with the computer off how will you do it. I know some old motherboards can do this.

 

[Bill_Bright]

As a precaution i'll lay the tower on its side.

If your cooler is very heavy, laying the tower in the side might put even more stress on the motherboard. An excessively heavy cooler should not be a problem except during transport and handling. This assumes all the necessary standoffs were inserted in the case before mounting the motherboard. WARNING - a common newbie and distracted pro mistake is to insert extra standoffs under the board. Cases are designed to support 1000s of different motherboards so they typically have more standoff mounting holes than motherboards have mounting holes.

So it is important to ensure there is a standoff under all motherboard mounting holes, but no extra standoffs - that is, ensure there is a standoff only where there is a corresponding motherboard mounting hole. There "should" be enough motherboard mounting holes and corresponding standoff mounting holes to support even very heavy CPU coolers during normal use. I do recommend, however, removing heavy coolers, especially tall, upright fan coolers if transporting the computer.