Laptop only works with 2GB RAM?

I tuned my laptop a bit with an external graphics card via mini PCIe. So connected via an mPCIe to PCIe x16 adapter and then noc power supply etc. Connected. Then he didn't want to start with, then tried around forever with settings in the bios etc. But didn't help. Until I took out a $ gb ddr3 RAM bar, suddenly it started, Graka recognized driver installed and everything was great, only that with 2gb Ram brings me very little. And I have no plan at all why it doesn't work with 6GB, what the hell could that be? So it can't be because of the 2 different bars because without external graphics card it works. Maybe there are too few PCIe lanes left to connect an external graphics card and 2 ram bars? But can't be because I deactivated the internal graphics card, and I don't even know if RAM is connected via PCIe at all… So I need a real expert now, but I don't know if I'm right with Girlfriend if here no expert finds, maybe I know a more suitable forum for this topic? Well now I hope for help here first, thank you in advance.

More suitable forums:

https://extreme.pcgameshardware.de/

https://www.computerbase.de/forum/

https://www.hardwareluxx.de/community/

I do not check how to post on pcgh, I signed up… Am I just lost af? How the hell is that

If you are logged in and are in the corresponding sub-forum, simply click on "Create topic".