<< Solved >> Broken Hardware after GPU switch

[BigOncleSam]

Hi guys,
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FIXED (thanks to [B]Shiitaki[/B]) by :
1) Removing CMOS battery and everything (except CPU ^^) from the MB
2) Waiting 2H
3) Plug CMOS battery, 24pin MB power cable to power supply, 1 RAM stick
4) LOOP: shutdown, unplug power cord, plug 1 item to MB, power on
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First, if this post doesn't belong in this section, please let me know.

Now the problem : TLDR; computer does not power :S
I have a build under High Sierra with those components :
MB : GA-Z97X-Gaming GT
CPU : i4790k
Alim : Corsair Gold 650W
GPU : GV-N970G1 GAMING-4GD

I finally decided to leave NVidia for AMD and brougth a MSI Radeon RX 480.
I removed the old GPU, plugged the new one and powered the computer.
I was surprised that everything was working fine. And without reading about upgrading to Catalina I dowloaded the firmware and started the upgrade.
Upon reboot, I got the charging bar and then a black screen... I allowed 20min to the process to continue and get me back my screen but nothing...
So I forced shutdown it and powered it again, nothing different... Then I tried to boot on a freshly made Catalina USB key but I got the same error.
After that 2nd deception, I got the idea to replug the old GPU and to start over the processus, same error...
I decided to try again with the AMD GPU again and this is where the nightmare happened... It didn't power at all.

I tried to remove all peripherals from the MB and to power... No power... The power button blink one time like there is a shortcircuit somewhere...

I am totally scared of having broken something but I dont know what and I dont know how...

I am asking to you how can I check each component to find the faulty one. Or if there is none, how to get it working all together again.

Thank you for reading and for your help.

You can ask me for any detail or picture.

Chap

 

[Shiitaki]

Heh, scary indeed.. I would ask if you flipped the switch on the power supply or pulled the power supply cord completely before moving cards around? Otherwise, it should not be catastrophic. I would look for any damage to any of the wires, unplug everything and then plug it back in. IF you have not, this included the power cord for the power supply. Most power supplies have a protection circuit that will be reset if you disconnect the power cord, thus why you should check for any damaged wires. If all of that checks out then it is still dead then I would find a known good power supply to try. Did I mention to check the front panel case connectors? Make sure the two pin power is connected? Just asking, please don't feel insulted.

IF the power supply is known good, the power cable to the front of the case is connected, still doesn't power up, I would disconnect from the power supply from the wall and remove the little CMOS battery on the motherboard and leave it overnight. Then with only one ram stick and CMOS battery reinstalled and literally everything else disconnected from the board except the 24 pin cable and the EPS(CPU power, usually 8pin) on the other side of the CPU from the 24 pin, manually bridge the 2 pins carefully for the front panel power button. If it is still dead remove the one ram stick and put a different one in a different slot and try shorting the power switch pins again. Asus boards sometimes have extra buttons next to he memory, that has worked in the past.

I have had this very kind of issue and I took 2 days getting it to work again and it has been Mojave now for 6 months without error, so don't give up too quick.

Once you can see the CPU fan spin up, turn the power supply off by pulling the cord or flipping the switch, if the power supply is so cheap it doesn't have a switch that is a different issue. Put the AMD card back in and short the pins again, if you get the bios screen on the monitor then power off again and connect the front panel connectors and then use the real case switch, if it doesn't work you manually short he pins again, thus verifying where the problem is. If the front panel works you power off and connect some more stuff and retest.

If all of this works don't be surprised to get everything connected again and working with no idea what was really the problem, this does annoyingly happen. Unless you are plugging and unplugging graphics cards in to the motherboard with the power supply still connected to power you should be able to get it back. There is always standby power going through the motherboard even when the computer is 'off' but connected to mains.

Good luck!!

 

[BigOncleSam]

Thank you so much for this reply !! I will try each step asap (and edit the main post following the state)

 

[BigOncleSam]

Wow I get it working again ! Thanks to your step by step guide.

First I remove the CMOS battery and waited 2h. After that, I unplugged everything except the 24 pin cable and 1 RAM, powered, it was ok. Then, 1 item at a time, I plugged back everything and it was fixed.

Thank you for your support