[SOLVED] Changing GPU - no boot

[Erik_11]

Hi all,

I bought an RTX 3070 to replace my "old" RX 580, which is still working fine by the way.
So I decided to give that to my brother with my PSU as well, to replace his RX 550.

My build:

R5 3600
Gigabyte Aorus B450 Elite
16GB DDR4

His build:

i5-6500
ASUS PRIME B250M-A
16GB DDR4

The problem is, when I swapped the cards, his PC won't show any display with the 580.
I tried with his old PSU, nothing. Put back to my PC, it works fine with my new PSU.

Tried tweaking PCI-E speed Auto, Gen3, Gen2, nothing.
Turned on and off CSM, cleaned PCI-E connectors, unplugged M.2, SATA, nothing.
Tried HDMI, DVI, nothing...

If I boot up with the iGPU with the 580 plugged in, I can't see it in the BIOS, but something can be seen in Windows device manager, something like unknown PCI-E device.
If I plug back the 550, everything is working like it used to.

And the other thing, is that a few years back we tried his PC with the 580, and it worked then.
There were a few Windows reinstalls since then, but I don't think that should matter, because I can't even see POST.

Can anybody help me whats going on? I'm furious about it, I spent hours on troubleshooting to no avail, supposed to be plug and play...

Thanks!

 

[rgd1101]

and the psu brand and model?

 

[Erik_11]

and the psu brand and model?

Thermaltake EVO BLUE 650W - this is the one I used the rx580 for years, and gave to my brother
chieftec arena 500w - brothers old psu
cooler master mwe 700w - my new psu

I dont think that these matter, because it works with my config.

 

[Erik_11]

Not so long ago, LTT posted a video, and they mentioned that their problem was fixed by reseating the CPU.
I tried that, and now the GPU works...