Graphic errors - is it the RAM or the SOC?

Hi, I have graphical errors and glitches on a switch.

I already reflowed both the CPU and the RAMs, but it’s still present.
I assume one of the RAMs is defective, am I right?

Is there any place to buy them preballed or must I Do it myself?

Thanks.

I would bet is a faulty SoC. Using logical from GPUs , bad SoC would show squares everywhere , ram failure would give patterns instead of squares . I would give it a reballing to both SoC and ram if still the same then SoC is bad