Forgetaboutit.
Too risky. The chips are soldered to the board using surface-mount technology, and the special tools required run thousands of dollars. If you decide to start such a project, you risk turning a working computer into electronic waste.
Improvements in today's RAM are NOT backward-compatible. They are mainly due to wildly different memory organization, NOT faster chips in the same form. They would require re-organizing to system-on-a-chip, which is not possible with the processor and Graphics used in your computer.
Computers are a commodity. They have no Art value. Every model with the same specs is worth about the same (unless abused and damaged.) Let go of that obsolete computer and save for a newer one that can better meet your needs, now and in the future.