Question 7900 XTX doing some strange things! Need Help PLEASE!

[jayxenogaming5]

Hey, recently I purchased a preowned 7900 xtx for a great price!
It still has warranty until May 2025
When I first got it on Monday 27/01/2025 it worked great, did some editing, gaming and light undervolting.
Suddenly as of yesterday my white vga light for my motherther board comes on, even when the computer boots into windows. The light also flickers while the pc is in use.
I thought it was strange but my motherboard is old so perhaps its glitching, but now I noticed that the amd driver don't recognise the gpu and the device manager says error code 43 on the gpu.
So I reinstalled the drivers and its working again but this morning after booting up, it says its unrecognised again. (White light is still on)

What is going on?
Never seen something like this!

(With my old 6800 XTthe white light occasionally came on but after a restart it would go away, and I didn't notice any other issues, this time it wont go away)

Specs:
GPU: RX 7900 XTX (ASUS TUF)
CPU: Ryzen 5800X3D
Motherboard: B450f Gaming II
PSU: Cooler Master V1000
RAM: 4x16gb 3200mhz cl16

 

[Peksha]

This is a post code indicator, it can't light up after booting. At least I've never seen anything like this. What you can check is the pcie connection and the power supply (both through the slot and from the power supply)

 

[jayxenogaming5]

So I have tried take the GPU out, resetting cmos, swapping ram around, take gpu pcie cables off and on.
Doesn't seem to get rid of the LED
Could it be my motherboard is faulty?
Just strange that the timing is after getting my new gpu and the vga light was flickering while using the pc yesterday.
Now its a solid white light

 

[Peksha]

Try other pcie speed in same slot, and insert into other slots (and motherboard from you friends)

 

[boju]

Still underclocked? Reinstalling drivers would revert that i think? It's possible the card, who knows how it was treated, does not like lower voltage now.

If troubles continue, since your old gpu didn't give you issues, should be giving your system more benefit of the doubt and return the card. There probably was a good reason why the card was sold at an attractive price.