PC wont power on - resolved

RobotXander · 25 Dec 2021 at 14:59

Hi Guys,

Hoping someone can offer some advice on Xmas day lol

]
Bought my son a new Ryzen 5 3600 CPU and Rog Strix B450F motherboard for Xmas

This was to replace an old motherboard that I assumed was faulty, along with an Athlon 3000G CPU (nice upgrade)

PC wouldn't power on before I bout the new CPU and Mobo - but after installing them both, it still wont power on.

Now - to keep things to the point:

PC wouldn't power on - have replaced the following:

PSU
MOBO
CPU

And still wont power on when pressing the power button.

Mobo and cooler lights all come on ok, but press the power button and nothing...

Also tried the screwdriver trick on the power pins, but nothing.

Next step is to strip it fully and restart from scratch, but any advice would be great

Merry christmas by the way

andy_mk3 · 25 Dec 2021 at 15:05

What's left over from the old build?

Might be worth building up the new motherboard outside of the case with the bare minimum installed (CPU, Cooler, 1 Stick of RAM, GPU and PSU) to ensure there are no external factors stopping it from powering on.

Also just to note, if you were previously using the onboard graphics of the 3000G, you will now need a GPU as the Ryzen 3600 has no integrated graphics.

RobotXander · 25 Dec 2021 at 15:07

Of course, should mention he also has a Strix 1060 GPU.

Only thing left over from the old build is Case, RAM and Asus AIO

edscdk · 25 Dec 2021 at 15:57

Disconnect everything that does not need to be connected Inc hdd, usb / case wiring.. Shot the power jumpers with a screwdriver see if it powers on

Then take it all out the case any try on the desk..

RobotXander · 27 Dec 2021 at 10:52

Quick update - Breadboarding helped me track down the issue

Barebones power on (using the screwdriver method) outside the case worked fine. Added all RAM and Graphics Card and all still powered on ok.

It was only when I got to the fan controller connection stage that I found the issue. It used a Molex connecter to power it, and the molex power cable coming from the PSU was not the EVGA cable (PSU is EVGA) but rather one of my NZXT ones...
Looks like it has a different pin layout, because as soon as it was plugged in - the pc wouldn't power on. Swapped for the correct EVGA one and powered on right away.

EsaT · 27 Dec 2021 at 11:59

Never mix cables from different PSUs.
Because of being made by different manufacturers/OEMs even PSUs of single brand can have different cabling pinouts.
And even actual manufacturers (Seasonic one of the rare ones) have changed cabling once or twice since modular cabling appeared into PSUs.

andy_mk3 · 27 Dec 2021 at 12:08

You were very lucky you didn't do any damage with that, lesson learnt though I hope

Plenty of people have killed Hard drives, SSDs, even GPUs doing that!

RobotXander · 27 Dec 2021 at 12:44

Indeed! Lesson learned for sure!
No idea how it got mixed up in there...at least it was just the fan controller it was connected to