Copy/paste the .sys files directly over the existing ones. All 3 of them. Reboot.
If you install new memory while keeping even 1 of the old, that is asking for more problems then you already have.
My advice stands as is, with good reason.
If you aren't going to get new memory and simply going to just remove the defective one and that's all .... then you can test one at a time in the slot closest to CPU, while removing others.